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Parent Category: Products

Category: Headphone Amplifier Measurements

Created: 10 January 2019

Reviewed on: SoundStage! Solo, January 2019

I measured the iFi Audio xCAN using a Clio 10 FW audio analyzer and a Neutrik NL-1 Minilyzer. Except as noted, I used the xCAN’s unbalanced analog input and unbalanced analog output, because I don’t yet have an adapter for 2.5mm balanced outputs I can use for measurements. Note that my focus with these tests is on measurements that confirm these devices’ basic functionality, and that gauge the efficacy of any special features and functions that might be measurable.

This chart shows the xCAN’s frequency response with all processing off, and with XBass II engaged in its three different modes (Bass, Presence, and Bass+Presence), with 1mW output into a 32-ohm load. With processing off, the response measures -0.14dB at 20Hz and -0.19dB at 20kHz. Bass mode boosts response by 9.96dB at 20Hz. Presence mode boosts response in a 4.12dB peak centered at 1288Hz. Frequency response did not change in 3D+ mode, and also did not change with 250-ohm and 600-ohm loads.

This chart shows the unbalanced output of the xCAN vs. total harmonic distortion (THD) into 32-, 250- and 600-ohm loads. Note that iFi’s power ratings are specified at 16, 50, 300 and 600 ohms, so some of my measurements are not directly comparable. Output into 32 ohms is 320mW at 0.5% THD and 336mW at 1% THD (iFi’s rating, in S-balanced/unbalanced mode, is 380mW into 32 ohms, THD unspecified). Output into 250 ohms is 46mW at 0.5% THD and 49mW at 1% THD. Output into 600 ohms is 20mW at 0.5% THD and 19mW at 1% THD.

Here you can see the harmonic distortion spectrum and noise floor of the xCAN, referenced to 3Vrms output at 600Hz into 32 ohms. The third harmonic at 1.8kHz is slightly more predominant than the second harmonic, which will sound a little more objectionable than an amp (like a typical tube amp) with predominantly second-harmonic distortion, but if you actually dare to listen at 3Vrms (280mW into 32 ohms), the distortion from the headphones will likely be far louder than the distortion from the amp.

I measured the unbalanced output impedance at 1.2 ohms at 1kHz; iFi rates impedance at <2 ohms for balanced and <1 ohm for unbalanced output. Regardless, the output impedance is low enough not to react significantly with the reactance of the headphones, and thus won’t change their frequency response.

. . . Brent Butterworth
brentb@soundstagenetwork.com

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Parent Category: Products

Category: Headphone Amplifier Measurements

Created: 01 October 2018

Reviewed on: SoundStage! Solo, October 2018

I measured the iFi Audio xDSD using a Clio 10 FW audio analyzer and a Neutrik NL-1 Minilyzer. For all of these tests, I used the xDSD’s coaxial digital input. Note that this is the first DAC-headphone amp I’ve measured for SoundStage! Solo; I’ve decided to focus my efforts on tests that confirm such devices’ basic functionality, and that gauge the efficacy of any special features and functions that might be measurable.

This chart shows the xDSD’s frequency response in its Listen and Measure modes, and with XBass+ engaged, with a 24-bit/192kHz S/PDIF signal and the xDSD set for 1mW output into a 32-ohm load. The response in both modes measured -0.16dB at 20Hz and -0.26dB at 20kHz. Listen mode actually measured slightly better here, with less rolloff above 65kHz; apparently, the switch is mislabeled. The bass boost in XBass+ mode was 6.48dB at 20Hz.

This chart shows the xDSD’s frequency response in Listen and Measure modes, and with XBass+ engaged, with a 16/48 S/PDIF signal and the xDSD set for 1mW output into a 32-ohm load. The treble response at 20kHz in Measure mode is -1.91dB, and in Listen mode -0.32dB. Definitely, the switch is mislabeled. According to the xDSD manual, the Listen filter is “transient-optimized minimum phase” and the Measure filter is “frequency response optimized,” but a filter with -1.91dB rolloff at 20kHz is certainly not “frequency response optimized.”

This chart shows the output of the xDSD vs. its total harmonic distortion (THD) into loads of 32, 250, and 600 ohms. Although iFi specifies the xDSD’s power output into 16, 50, 300, and 600 ohms, which renders most of my measurements not directly comparable, those measurements do suggest that iFi’s specs are on the mark. The xDSD’s output into 32 ohms is 291mW at 0.5% THD and 304mW at 1% THD; into 250 ohms, the output is 53mW at 0.5% THD and 54mW at 1% THD; and into 600 ohms, the xDSD puts out 22mW at 0.5% THD and 23mW at 1% THD.

Here you can see the xDSD’s spectrum of harmonic distortion and noise floor when driven by a 24/192 S/PDIF signal and referenced to 1.5V RMS output at 600Hz. Note that the distortion profile of the Measure and Listen modes is effectively the same.

I measured the xDSD’s output impedance as 0.8 ohm at 1kHz, which confirms iFi’s rating of <1 ohm. I prefer a headphone amp’s output impedance to be 1 ohm or less; the output impedance will then not react significantly with the reactance of the headphones, and thus won’t affect the ’phones’ frequency response.

. . . Brent Butterworth
brentb@soundstagenetwork.com

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Parent Category: Products

Category: Amplifier Measurements

Created: 15 February 2026

Link: reviewed by Roger Kanno on SoundStage! Hi-Fi on February 15, 2026

General Information

All measurements taken using an Audio Precision APx555 B Series analyzer.

The Hegel Music Systems H150 was conditioned for 1 hour at 1/8th full rated power (~9W into 8 ohms) before any measurements were taken. All measurements were taken with both channels driven, using a 120V/20A dedicated circuit, unless otherwise stated.

The H150 offers two sets of line-level analog inputs (RCA and XLR), one RCA phono MM input, three digital S/PDIF inputs (two optical over Toslink and one coaxial over RCA), one USB digital input, left/right pre-outs, one set of speaker-level outputs, and one headphone output over 1/4″ TRS connector. A Bluetooth input is also offered. For the purposes of these measurements, the following inputs were evaluated: digital coaxial, analog (XLR) line-level and phono (RCA), as well as the headphone output. There were no appreciable differences between the RCA and XLR line-level inputs in terms of gain, THD, and noise. Nonetheless, 1kHz FFTs are provided for each in this report.

Most measurements were made with a 2Vrms line-level analog input and 0dBFS digital input. The signal-to-noise ratio (SNR) measurements were made with the default input signal values but with the volume set to achieve the achievable output power of 75W into 8 ohms. For comparison, on the line-level input, a SNR measurement was also made with the volume at maximum.

Based on the accuracy and randomness of the left/right volume channel matching (see table below), the H150 volume control is digitally controlled but operating in the analog domain. The H150 overall volume range is from -70dB to +31.6dB (line-level input, speaker output). It offers 2-3dB increments from position 0 to 9, then 1dB increments from positions 10 to 100. Of note, some volume steps offer no change in output level.

Our typical input bandwidth filter setting of 10Hz-22.4kHz was used for all measurements except FFTs and THD versus frequency, where a bandwidth of 10Hz-90kHz was used. Frequency response measurements utilize a DC to 1 MHz input bandwidth.

Volume-control accuracy (measured at speaker outputs): left-right channel tracking

Published specifications vs. our primary measurements

The table below summarizes the measurements published by Hegel for the H150 compared directly against our own. The published specifications are sourced from Hegel’s website, either directly or from the manual available for download, or a combination thereof. With the exception of frequency response, where the Audio Precision bandwidth was extended to 1MHz, assume, unless otherwise stated, 10W into 8ohms and a measurement input bandwidth of 10Hz to 22.4kHz, and the worst-case measured result between the left and right channels.

Our primary measurements revealed the following using the line-level analog input and digital coaxial input (unless specified, assume a 1kHz sinewave at 2Vrms or 0dBFS, 10W output, 8-ohm loading, 10Hz to 22.4kHz bandwidth): 

For the continuous dynamic power test, the H150 was able to sustain 134W into 4 ohms (~3% THD) using an 80Hz tone for 500ms, alternating with a signal at -10dB of the peak (13.4W) for 5 seconds, for 5 minutes without inducing a fault protection circuit. This test is meant to simulate sporadic dynamic bass peaks in music and movies. During the test, the top of the H150 was hot to the touch.

Our primary measurements revealed the following using the phono-level input, MM configuration (unless specified, assume a 1kHz 5mVrms sinewave input, 10W output, 8-ohm loading, 10Hz to 22.4kHz bandwidth):

Our primary measurements revealed the following using the analog input at the headphone output (unless specified, assume a 1kHz sinewave, 2Vrms input/output, 300 ohms loading, 10Hz to 22.4kHz bandwidth):

Frequency response (8-ohm loading, line-level input)

In our frequency-response plots above (relative to 1kHz), measured across the speaker outputs at 10W into 8 ohms, the H150 is near flat within the audioband (20Hz/20kHz, -0.2/-0.05dB). The -3dB point is beyond 200kHz. The H150 appears to be AC coupled, demonstrated by it being -2dB at 5Hz. In the graph above and most of the graphs below, only a single trace may be visible. This is because the left channel (blue or purple trace) is performing identically to the right channel (red or green trace), and so they perfectly overlap, indicating that the two channels are ideally matched.

Phase response (8-ohm loading, line-level input)

Above are the phase-response plots from 20Hz to 20kHz for the line-level input, measured across the speaker outputs at 10W into 8 ohms. The H150 did not invert polarity and yielded only about +10 degrees of phase shift at 20Hz, and -10 degrees at 20kHz.

Frequency response (8-ohm loading, MM phono input)

The chart above shows the frequency response (relative to 1kHz) for the MM phono input. What is shown is the deviation from the RIAA curve, where the input signal sweep is EQ’d with an inverted RIAA curve supplied by Audio Precision (i.e., zero deviation would yield a flat line at 0dB). We see a very small channel-to-channel deviations below 1kHz (within 0.1dB), but as much as 0.7dB deviations between 5kHz and 20kHz. At 20Hz, the response is down about 2.5dB. Between 50Hz to 20kHz, RIAA deviations are within +/- 0.5dB for the left channel, and +/- 0.2dB for the right channel.

Phase response (8-ohm loading, MM phono input)

Above is the phase-response plot from 20Hz to 20kHz for the MM phono input, measured across the speaker outputs at 10W into 8 ohms. The H150 does not invert polarity. For the phono input, since the RIAA equalization curve must be implemented, which ranges from +19.9dB (20Hz) to -32.6dB (90kHz), phase shift at the output is inevitable. Here we find a worst case of about +40 degrees at 20Hz and -90 degrees at 20kHz.

Frequency response vs. input type (8-ohm loading, left channel only)

The chart above shows the H150’s frequency response (relative to 1kHz) as a function of input type measured across the speaker outputs at 10W into 8 ohms. The two green traces are the same analog input data from the speaker-level frequency-response graph above (but limited to 80kHz). The blue and red traces are for a 16-bit/44.1kHz dithered digital input signal from 5Hz to 22kHz using the coaxial input, the purple and green traces are for a 24/96 dithered digital input signal from 5Hz to 48kHz, and the pink and orange traces are for a 24/192 dithered digital input signal. All signal sweeps yielded the same -2dB at 5Hz response. The -3dB points are: 21kHz for the 16/44.1 data, 46kHz for the 24/96, 50.3kHz for the 24/192 data. Also of note, all digital inputs showed brick-wall-type high-frequency filtering, with a 0.5-1dB rise in response past 20kHz.

Digital linearity (16/44.1 and 24/96 data)

The chart above shows the results of a linearity test for the coaxial digital input for both 16/44.1 (blue/red) and 24/96 (purple/green) input data, measured at the line-level pre-outputs of the H150, where 0dBFS was set to yield 2Vrms. For this test, the digital input is swept with a dithered 1kHz input signal from -120dBFS to 0dBFS, and the output is analyzed by the APx555. The ideal response would be a straight flat line at 0dB. Both data were essentially perfect as of -100dBFS down to 0dBFS. The 24/96 data werewithin 0.5dB at -120dBFS, while the 16/44.1 data were +2dB at -120dBFS.

Impulse response (24/44.1 data)

The graph above shows the impulse response for a looped 24/44.1 test file that moves from digital silence to full 0dBFS (all “1”s) for one sample period then back to digital silence, measured at the line-level pre-outs of H150. We see a typical symmetrical sinc function response.

J-Test (coaxial)

The chart above shows the results of the J-Test test for the coaxial digital input measured at the line-level pre-outputs of the H150 where 0dBFS is set to 2Vrms. J-Test was developed by Julian Dunn in the 1990s. It is a test signal—specifically, a -3dBFS undithered 12kHz squarewave sampled (in this case) at 48kHz (24 bits). Since even the first odd harmonic (i.e., 36kHz) of the 12kHz squarewave is removed by the bandwidth limitation of the sampling rate, we are left with a 12kHz sinewave (the main peak). In addition, an undithered 250Hz squarewave at -144dBFS is mixed with the signal. This test file causes the 22 least significant bits to constantly toggle, which produces strong jitter spectral components at the 250Hz rate and its odd harmonics. The test file shows how susceptible the DAC and delivery interface are to jitter, which would manifest as peaks above the noise floor at 500Hz intervals (e.g., 250Hz, 750Hz, 1250Hz, etc.). Note that the alternating peaks are in the test file itself, but at levels of -144dBrA and below.  The test file can also be used in conjunction with artificially injected sinewave jitter by the Audio Precision, to show how well the DAC rejects jitter.

Here we see a mediocre J-Test result, with several peaks in the audioband, ranging from -115dBFS down to -150dBFS. This is an indication that the H150 DAC may have average jitter immunity.

J-Test (optical)

The chart above shows the results of the J-Test test for the optical digital input measured at the line-level pre-outputs of the H150. The optical input yielded essentially the same result compared to the coaxial input.

J-Test (coaxial, 10ns jitter)

The chart above shows the results of the J-Test test for the coaxial digital input measured at the line-level output of the H150, with an additional 10ns of 2kHz sinewave jitter injected by the APx555. At this level of jitter, we do not see the tell-tale peaks at 10kHz and 12kHz. The optical input yielded the same result.

J-Test (coaxial, 100ns jitter)

The chart above shows the results of the J-Test test for the coaxial digital input measured at the line-level output of the H150, with an additional 100ns of 2kHz sinewave jitter injected by the APx555. The telltale peaks at 10kHz and 12kHz can be seen at -100dBFS. The optical input yielded the same result.

Wideband FFT spectrum of white noise and 19.1kHz sine-wave tone (coaxial input)

The chart above shows a fast Fourier transform (FFT) of the H150’s line-level pre-outputs with white noise at -4dBFS (blue/red) and a 19.1 kHz sinewave at 0dBFS fed to the coaxial digital input, sampled at 16/44.1. The steep roll-off around 20kHz in the white-noise spectrum shows the filter is of the brickwall-type variety. There are a few low-level aliased image peaks within the audioband at the -110 to -115dBrA level. The primary aliasing signal at 25kHz is highly suppressed and buried in the -145dBrA noise floor.

RMS level vs. frequency vs. load impedance (1W, left channel only)

The chart above shows RMS level (relative to 0dBrA, which is 1W into 8 ohms or 2.83Vrms) as a function of frequency, for the analog line-level input swept from 5Hz to 50kHz. The blue plot is into an 8-ohm load, the purple is into a 4-ohm load, the pink plot is an actual speaker (Focal Chora 806, measurements can be found here), and the cyan plot is no load connected. The chart below . . .

. . . is the same but zoomed in to highlight differences. Here we see that the deviations between no load and 4 ohms are very small at roughly 0.05dB. This is a strong result and an indication of a low output impedance, or high damping factor. With a real speaker load, deviations measured roughly the same at 0.06dB.

THD ratio (unweighted) vs. frequency vs. output power

The chart above shows THD ratios at the speaker-level outputs into 8 ohms as a function of frequency for a sinewave stimulus at the analog line-level input. The blue and red plots are for the left and right channels at 1W output into 8 ohms, purple/green at 10W, and pink/orange at 72W. The power was varied using the H150’s volume control. The 1 and 10W THD ratios were closely clustered together (within roughly 5dB), and ranged from 0.006% (200-400Hz) to 0.03% (20kHz). At 72W, THD ratios ranged from 0.15% at lower frequencies, up to 0.7% at 20kHz.

THD ratio (unweighted) vs. frequency at 10W (phono input, MM)

The chart above shows THD ratios as a function of frequency plots for the MM phono input measured across an 8-ohm load at 10W. The input sweep is EQ’d with an inverted RIAA curve. The THD values for the right channel varied from around 0.4% (20Hz) down to 0.009% (2/3kHz), up to 0.02% at 20kHz. The left channel yielded THD ratios up to roughly 5dB higher than the right channel.

THD ratio (unweighted) vs. output power at 1kHz into 4 and 8 ohms

The chart above shows THD ratios measured at the speaker-level outputs of the H150 as a function of output power for the analog line-level input for an 8-ohm load (blue/red for left/right) and a 4-ohm load (purple/green for left/right). THD ratios into 4 and 8 ohms are close (within 5dB), and the left channel outperformed the right by approximately 3dB. The 8-ohm (left) data range from 0.006% at 50mW, down to 0.004% in the 10 to 30W range. The “knee” into 8 ohms can be found right around 50W, while the 4-ohm “knee” can be seen around 75W. The 1% THD marks were hit at 81W and 121W into 8 and 4 ohms.

THD+N ratio (unweighted) vs. output power at 1kHz into 4 and 8 ohms

The chart above shows THD+N ratios measured at the speaker-level outputs of the H150 as a function of output power for the analog line-level input for an 8-ohm load (blue/red for left/right) and a 4-ohm load (purple/green for left/right). THD+N ratios into 4 and 8 ohms are close (within 3-5dB). The 8-ohm data range from 0.02% at 50mW, down to 0.005% in the 20 to 50W range.

THD ratio (unweighted) vs. frequency at 8, 4, and 2 ohms (left channel only)

The chart above shows THD ratios measured at the output of the H150 as a function of frequency into three different loads (8/4/2 ohms) for a constant input voltage that yields 20W at the output into 8 ohms (and roughly 40W into 4 ohms, and 80W into 2 ohms) for the analog line-level input. The 8-ohm load is the blue trace and the 4-ohm load the purple trace. We find a small 2-3dB increase in THD from 8 to 4 ohms. These data ranged from 0.006% at 20Hz down to 0.003% at 100-200Hz (8 ohms), then up to 0.03% at 20kHz. The 2-ohm load data was fairly constant at a high 15-20% THD.

THD ratio (unweighted) vs. frequency into 8 ohms and real speakers (left channel only)

The chart above shows THD ratios measured at the output of the H150 as a function of frequency into an 8-ohm load and two different speakers for a constant output voltage of 2.83Vrms (1W into 8 ohms) for the analog line-level input. The 8-ohm load is the blue trace, the purple plot is a two-way speaker (Focal Chora 806, measurements can be found here), and the pink plot is a three-way speaker (Paradigm Founder Series 100F, measurements can be found here). Generally, THD ratios for all three plots are tightly clustered together, which is a strong result, though the absolute THD ratios are not particularly low for a solid-state amplifier. THD ratios range between 0.06% at 20Hz for the two-way speaker (0.02% for the three-way speaker and resistive load), down to between 0.006% and 0.01% between 60Hz and 1kHz, then up to 0.04% at 20kHz.

IMD ratio (CCIF) vs. frequency into 8 ohms and real speakers (left channel only)

The chart above shows intermodulation distortion (IMD) ratios measured at the output of the H150 as a function of frequency into an 8-ohm load and two different speakers for a constant output voltage of 2.83Vrms (1W into 8 ohms) for the analog line-level input. Here the CCIF IMD method was used, where the primary frequency is swept from 20kHz (F1) down to 2.5kHz, and the secondary frequency (F2) is always 1kHz lower than the primary, with a 1:1 ratio. The CCIF IMD analysis results are the sum of the second (F1-F2 or 1kHz) and third modulation products (F1+1kHz, F2-1kHz). The 8-ohm load is the blue trace, the purple plot is a two-way speaker (Focal Chora 806, measurements can be found here), and the pink plot is a three-way speaker (Paradigm Founder Series 100F, measurements can be found here). We find that all three IMD traces are essentially identical, hovering between the 0.01% and 0.03% level.

IMD ratio (SMPTE) vs. frequency into 8 ohms and real speakers (left channel only)

The chart above shows IMD ratios measured at the output of the H150 as a function of frequency into an 8-ohm load and two different speakers for a constant output voltage of 2.83Vrms (1W into 8 ohms) for the analog line-level input. Here, the SMPTE IMD method was used, where the primary frequency (F1) is swept from 250Hz down to 40Hz, and the secondary frequency (F2) is held at 7kHz with a 4:1 ratio. The SMPTE IMD analysis results consider the second (F2 ± F1) through the fifth (F2 ± 4xF1) modulation products. The 8-ohm load is the blue trace, the purple plot is a two-way speaker (Focal Chora 806, measurements can be found here), and the pink plot is a three-way speaker (Paradigm Founder Series 100F, measurements can be found here). We find very similar IMD ratios into all three loads; 0.03% from 40Hz to 250Hz, 0.01-0.02% from 300Hz to 500Hz, and 0.005% from 500Hz to 1kHz.

FFT spectrum – 1kHz (line-level input, XLR)

Shown above is the fast Fourier transform (FFT) for a 1kHz input sinewave stimulus, measured at the output across an 8-ohm load at 10W for the analog XLR line-level input. We see that the signal’s second (2kHz) and third (3kHz) harmonic dominate at roughly -80dBrA, or 0.01%. There are subsequent signal harmonics visible at -90dBrA, or 0.003%, and below. On the right side of the signal peak, we find power-supply-related noise peaks, with the second harmonic (120Hz) dominating at -95dBrA, or 0.002%. Other noise peaks can be seen at and below the -110dBrA, or 0.0003% level.

FFT spectrum – 1kHz (line-level input, RCA)

Shown above is the fast Fourier transform (FFT) for a 1kHz input sinewave stimulus, measured at the output across an 8-ohm load at 10W for the analog RCA line-level input. We see effectively the same result as with the XLR 1kHz FFT above.

FFT spectrum – 1kHz (MM phono input)

Shown above is the fast Fourier transform (FFT) for a 1kHz input sinewave stimulus, measured at the output across an 8-ohm load at 10W for the analog phono input. We see that the signal’s second (2kHz) harmonic dominates at -70/-80dBrA (left/right), or 0.03/0.01%. There are subsequent signal harmonics visible at and below the -90dBrA, or 0.003%, level. On the right side of the signal peak, we find power-supply-related noise peaks, with the primary (60Hz), second (102Hz) and fourth (240Hz) harmonics dominating at between -50dBrA and -60dBrA, or 0.3 to 0.1%. Other noise peaks can be seen at and below the -80dBrA, or 0.01%, level.

FFT spectrum – 1kHz (digital input, 16/44.1 data at 0dBFS)

Shown above is the fast Fourier transform (FFT) for a 1kHz input sinewave stimulus, measured at the output across an 8-ohm load at 10W for the coaxial digital input, sampled at 16/44.1. The result is very similar to the analog line-level 1kHz FFT above.

FFT spectrum – 1kHz (digital input, 24/96 data at 0dBFS)

Shown above is the fast Fourier transform (FFT) for a 1kHz input sinewave stimulus, measured at the output across an 8-ohm load at 10W for the coaxial digital input, sampled at 24/96. The result is very similar to the 16/44.1 1kHz FFT above, but for a lower noise floor here due to the increased bit depth.

FFT spectrum – 1kHz (digital input, 16/44.1 data at -90dBFS)

Shown above is the FFT for a 1kHz -90dBFS dithered 16/44.1 input sinewave stimulus at the coaxial digital input, measured at the output across an 8-ohm load. We see the 1kHz primary signal peak, at the correct amplitude, with no distinguishable signal harmonics above the -135dBrA noise floor, and power-supply-related noise peaks at -110dBrA, or 0.0003%, and below.

FFT spectrum – 1kHz (digital input, 24/96 data at -90dBFS)

Shown above is the FFT for a 1kHz -90dBFS dithered 24/96 input sinewave stimulus at the coaxial digital input, measured at the output across an 8-ohm load. We see the 1kHz primary signal peak, at the correct amplitude, with no distinguishable signal harmonics above the -140dBrA noise floor, and power-supply-related noise peaks at -110dBrA, or 0.0003%, and below.

FFT spectrum – 50Hz (line-level input)

Shown above is the FFT for a 50Hz input sinewave stimulus measured at the output across an 8-ohm load at 10W for the analog line-level input. The X axis is zoomed in from 40Hz to 1kHz, so that peaks from noise artifacts can be directly compared against peaks from the harmonics of the signal. The most predominant (non-signal) peak is the second (100Hz) signal harmonic at -80dBrA, or 0.01%, followed by the third signal harmonic (150Hz) at -90dBrA, or 0.003%. Power-supply-related noise peaks can be seen at -100dBrA, or 0.001%, and below.

FFT spectrum – 50Hz (MM phono input)

Shown above is the FFT for a 50Hz input sinewave stimulus measured at the output across an 8-ohm load at 10W for the MM phono input. The X axis is zoomed in from 40 Hz to 1kHz, so that peaks from noise artifacts can be directly compared against peaks from the harmonics of the signal. The most predominant (non-signal) peaks are the 60Hz and 120Hz power-supply-related noise peaks at just above -60dBrA, or 0.1%. The highest signal harmonic is at 100Hz, at -60dBrA, or 0.1%.

Intermodulation distortion FFT (18kHz + 19kHz summed stimulus, line-level input)

Shown above is an FFT of the intermodulation distortion (IMD) products for an 18kHz + 19kHz summed sinewave stimulus tone measured at the output across an 8-ohm load at 10W for the analog line-level input. The input RMS values are set at -6.02dBrA so that, if summed for a mean frequency of 18.5kHz, would yield 10W (0dBrA) into 8 ohms at the output. We find that the second-order modulation product (i.e., the difference signal of 1kHz) is at -90dBrA, or 0.003%, while the third-order modulation products, at 17kHz and 20kHz, are just below the -80dBrA, or 0.01%, level.

Intermodulation distortion FFT (line-level input, APx 32 tone)

Shown above is the FFT of the speaker-level output of the H150 with the APx 32-tone signal applied to the analog input. The combined amplitude of the 32 tones is the 0dBrA reference, and corresponds to 10W into 8 ohms. The intermodulation products—i.e., the “grass” between the test tones—are distortion products from the amplifier and are at below the -100dBrA, or 0.001%, level.

Intermodulation distortion FFT (18kHz + 19kHz summed stimulus, coaxial digital input, 16/44.1)

Shown above is an FFT of the intermodulation distortion (IMD) products for an 18kHz + 19kHz summed sinewave stimulus tone measured at the output across an 8-ohm load at 10W for the digital coaxial input at 16/44.1 (-1dBFS).  We find that the second-order modulation product (i.e., the difference signal of 1kHz) is at -90dBrA, or 0.003%, while the third-order modulation products, at 17kHz and 20kHz, are just below the -80dBrA, or 0.01%, level.

Intermodulation distortion FFT (18kHz + 19kHz summed stimulus, coaxial digital input, 24/96)

Shown above is an FFT of the intermodulation distortion (IMD) products for an 18kHz + 19kHz summed sinewave stimulus tone measured at the output across an 8-ohm load at 10W for the digital coaxial input at 24/96 (-1dBFS). We find that the second-order modulation product (i.e., the difference signal of 1kHz) is at -90dBrA, or 0.003%, while the third-order modulation products, at 17kHz and 20kHz, are just below the -80dBrA, or 0.01%, level.

Intermodulation distortion FFT (18kHz + 19kHz summed stimulus, MM phono input)

Shown above is an FFT of the intermodulation distortion (IMD) products for an 18kHz + 19kHz summed sinewave stimulus tone measured at the output across an 8-ohm load at 10W for the MM phono input. We find that the second-order modulation product (i.e., the difference signal of 1kHz) is at -70/-80dBrA (left/right), or 0.03/0.01%, while the third-order modulation products, at 17kHz and 20kHz, are just below the -80dBrA, or 0.01%, level.

Squarewave response (10kHz)

Above is the 10kHz squarewave response using the analog line-level input, at roughly 10W into 8 ohms. Due to limitations inherent to the Audio Precision APx555 B Series analyzer, this graph should not be used to infer or extrapolate the H150’s slew-rate performance. Rather, it should be seen as a qualitative representation of the H150’s high bandwidth. An ideal squarewave can be represented as the sum of a sinewave and an infinite series of its odd-order harmonics (e.g., 10kHz + 30kHz + 50kHz + 70kHz . . .). A limited bandwidth will show only the sum of the lower-order harmonics, which may result in noticeable undershoot and/or overshoot, and softening of the edges. In this case, we find very clean/sharp corners.

Damping factor vs. frequency (20Hz to 20kHz)

The final graph above is the damping factor as a function of frequency. We can see damping factors ranging between roughly 200 and 300 for the left channel, and 150 and 200 for the right channel.

Diego Estan
Electronics Measurement Specialist

Details

Parent Category: Products

Category: Amplifier Measurements

Created: 15 February 2026

Link: reviewed by Phil Gold on SoundStage! Ultra on February 15, 2026

General Information

All measurements taken using an Audio Precision APx555 B Series analyzer.

The Burmester 232 was conditioned for 1 hour at 1/8th full rated power (~12W into 8 ohms) before any measurements were taken. All measurements were taken with both channels driven, using a 120V/20A dedicated circuit, unless otherwise stated.

The 232 under test came equipped with the optional digital module and offers two sets of line-level analog inputs (both XLR), three digital inputs (RCA, optical, XLR), left/right pre-outs (XLR), one set of speaker level outputs, and one headphone output over 1/4” TRS connector. Streaming options are also offered. For the purposes of these measurements, the following inputs were evaluated: digital coaxial (RCA), analog (XLR), as well as the headphone output.

Most measurements were made with a 4Vrms line-level analog input and 0dBFS digital input. The signal-to-noise ratio (SNR) measurements were made with the default input signal values but with the volume set to achieve the maximum (1% THD) output power of 90W into 8 ohms. For comparison, on the line-level input, a SNR measurement was also made with the volume at maximum.

Based on the accuracy and randomness of the left/right volume channel matching (see table below), the 232 volume control is digitally controlled but operating in the analog domain. The 232 overall volume range is from -57dB to +23dB (line-level input, speaker output). It offers 0.5 to 3dB increments over 60 steps.

Our typical input bandwidth filter setting of 10Hz-22.4kHz was used for all measurements except FFTs and THD versus frequency, where a bandwidth of 10Hz-90kHz was used. Frequency response measurements utilize a DC to 1 MHz input bandwidth.

Volume-control accuracy (measured at speaker outputs): left-right channel tracking

Published specifications vs. our primary measurements

The table below summarizes the measurements published by Burmester for the A232 compared directly against our own. The published specifications are sourced from Burmester’s website, either directly or from the manual available for download, or a combination thereof. With the exception of frequency response, where the Audio Precision bandwidth was extended to 1MHz, assume, unless otherwise stated, 10W into 8 ohms and a measurement input bandwidth of 10Hz to 22.4kHz, and the worst-case measured result between the left and right channels.

Our primary measurements revealed the following using the line-level analog input and digital coaxial input (unless specified, assume a 1kHz sinewave at 4Vrms or 0dBFS, 10W output, 8-ohm loading, 10Hz to 22.4kHz bandwidth):

For the continuous dynamic power test, the 232 was able to sustain 162W into 4 ohms (~3% THD) using an 80Hz tone for 500ms, alternating with a signal at -10dB of the peak (16.2W) for 5 seconds, for 5 minutes without inducing any fault protection. This test is meant to simulate sporadic dynamic bass peaks in music and movies. During the test, the sides of the 232 were only slightly warm to the touch.

Our primary measurements revealed the following using the analog input at the headphone output (unless specified, assume a 1kHz sinewave, 4Vrms input/2Vrms output, 300 ohms loading, 10Hz to 22.4kHz bandwidth):

Frequency response (8-ohm loading, line-level input)

In our frequency response plots above (relative to 1kHz), measured across the speaker outputs at 10W into 8 ohms, the 232 is essentially perfectly flat within the audioband (20Hz/20kHz, 0/-0.1dB). The -3dB point is at roughly 130kHz, and 0dB at 5Hz. The 232 appears to be DC-coupled. In the graph above and most of the graphs below, only a single trace may be visible. This is because the left channel (blue or purple trace) is performing identically to the right channel (red or green trace), and so they perfectly overlap, indicating that the two channels are ideally matched.

Frequency response sub-out (8-ohm loading, line-level input)

Above is the frequency response plot (relative to 20Hz) of the line-level sub-out, measured up to 80kHz. We find the same response as the speaker-level outputs and no low-pass filter applied.

Phase response (8-ohm loading, line-level input)

Above are the phase-response plots from 20Hz to 20kHz for the line-level input, measured across the speaker outputs at 10W into 8 ohms. The 232 appears to invert polarity (-180 degrees of phase shift); however, this is likely due to an XLR pin-out assignment that is different from the convention used by the audio analyzer. Ignoring the phase inversion, the 232 yielded only -20 degrees of phase shift at 20kHz.

Frequency response vs. input type (8-ohm loading, left channel only)

The chart above shows the 232’s frequency response (relative to 1kHz) as a function of input type measured across the speaker outputs at 10W into 8 ohms. The two green traces are the same analog input data from the speaker-level frequency-response graph above, but limited to 80kHz. The blue and red traces are for a 16-bit/44.1kHz dithered digital input signal from 5Hz to 22kHz using the coaxial input, the purple and green traces are for a 24/96 dithered digital input signal from 5Hz to 48kHz, and the pink and orange traces are for a 24/192 dithered digital input signal. At low frequencies, the digital signals yielded a flat response down to 5Hz, same as the analog response. The -3dB points are: just past 20kHz for the 16/44.1 data, 46kHz for the 24/96, just shy of 90kHz for the 24/192 data, and 130kHz for the analog input. Also of note, the digital plots showed brick-wall-type filtering around half the sampling frequencies, as well as rippling (+/-0.2dB) in the response at high frequencies.

Digital linearity (16/44.1 and 24/96 data)

The chart above shows the results of a linearity test for the coaxial digital input for both 16/44.1 (blue/red) and 24/96 (purple/green) input data, measured at the line-level pre-outputs of the 232, where 0dBFS was set to yield 2Vrms. The digital input is swept with a dithered 1kHz input signal from -120dBFS to 0dBFS, and the output is analyzed by the APx555. The ideal response would be a straight flat line at 0dB. Both data were essentially perfect as of -100dBFS down to 0dBFS. The 24/96 data were at 0dB at -120dBFS, while the 16/44.1 data were +2/0dB at -120dBFS. We extended the sweep to -140dBFS . . .

…where we found the 24/96 plot only overshot by +2/+4dB at -140dBFS. An excellent result.

Impulse response (24/44.1 data)

The graph above shows the impulse response for a looped 24/44.1 test file that moves from digital silence to full 0dBFS (all “1”s) for one sample period then back to digital silence, measured at the line-level pre-outs of 232. The impulse shows an inverted response; however, this is likely due to an XLR pin-out assignment that is different from the convention used by the audio analyzer. Ignoring the phase inversion, the 232 appears to implement a typical symmetrical sinc function filter.

J-Test (coaxial)

The chart above shows the results of the J-Test Test for the coaxial digital input measured at the line-level pre-outputs of the 232 where 0dBFS is set to 2Vrms. J-Test was developed by Julian Dunn the 1990s. It is a test signal—specifically, a -3dBFS undithered 12kHz squarewave sampled (in this case) at 48kHz (24 bits). Since even the first odd harmonic (i.e., 36kHz) of the 12kHz squarewave is removed by the bandwidth limitation of the sampling rate, we are left with a 12kHz sinewave (the main peak). In addition, an undithered 250Hz squarewave at -144dBFS is mixed with the signal. This test file causes the 22 least significant bits to constantly toggle, which produces strong jitter spectral components at the 250Hz rate and its odd harmonics. The test file shows how susceptible the DAC and delivery interface are to jitter, which would manifest as peaks above the noise floor at 500Hz intervals (e.g., 250Hz, 750Hz, 1250Hz, etc.). Note that the alternating peaks are in the test file itself, but at levels of -144dBrA and below.  The test file can also be used in conjunction with artificially injected sinewave jitter by the Audio Precision, to show how well the DAC rejects jitter.

Here we see a strong J-Test result, with only two small spurious peaks in the audioband at -150dBFS. This is an indication that the 232 DAC should have strong jitter immunity.

J-Test (optical)

The chart above shows the results of the J-Test test for the optical digital input measured at the line-level pre-outputs of the 232. The optical input yielded essentially the same results compared to the coaxial input.

J-Test (AES-EBU)

The chart above shows the results of the J-Test test for the AES-EBU XLR digital input measured at the line-level pre-outputs of the 232. We see essentially the same results compared to the coaxial input.

J-Test (coaxial, 10ns jitter)

The chart above shows the results of the J-Test test for the coaxial digital input measured at the line-level output of the 232, with an additional 10ns of 2kHz sinewave jitter injected by the APx555. The telltale peaks at 10kHz and 12kHz cannot be seen. The optical and AES-EBU showed the same results.

J-Test (coaxial, 100ns jitter)

The chart above shows the results of the J-Test test for the coaxial digital input measured at the line-level output of the 232, with an additional 100ns of 2kHz sinewave jitter injected by the APx555. This time the telltale peaks at 10kHz and 12kHz can be seen, but only at a very low -135dBFS. The optical and AES-EBU inputs yielded the same results. Another indication of strong jitter immunity.

Wideband FFT spectrum of white noise and 19.1kHz sine-wave tone (coaxial input)

The chart above shows a fast Fourier transform (FFT) of the 232’s line-level pre-outputs with white noise at -4dBFS (blue/red) and a 19.1 kHz sinewave at 0dBFS fed to the coaxial digital input, sampled at 16/44.1. The steep roll-off around 20kHz in the white-noise spectrum shows the implementation of a filter of the brick-wall-type variety. There are no low-level aliased image peaks within the audioband above the -135dBrA noise floor. The primary aliasing signal at 25kHz is highly suppressed at -100dBrA, while the second and third distortion harmonics (38.2, 57.3kHz) of the 19.1kHz tone are near the same level.

RMS level vs. frequency vs. load impedance (1W, left channel only)

The chart above shows RMS level (relative to 0dBrA, which is 1W into 8 ohms or 2.83Vrms) as a function of frequency, for the analog line-level input swept from 5Hz to 50kHz. The blue plot is into an 8-ohm load, the purple is into a 4-ohm load, the pink plot is an actual speaker (Focal Chora 806, measurements can be found here), and the cyan plot is no load connected. The chart below . . .

. . . is the same but zoomed in to highlight differences. Here we see that the deviations between no load and 4 ohms are extremely small at roughly 0.01dB. This is a strong result and an indication of an extraordinarily low output impedance, or extremely high damping factor. With a real speaker load, deviations measured lower at roughly 0.006dB.

THD ratio (unweighted) vs. frequency vs. output power

The chart above shows THD ratios at the speaker-level outputs into 8 ohms as a function of frequency for a sinewave stimulus at the analog line-level input. The blue and red plots are for the left and right channel at 1W output into 8 ohms, purple/green at 10W, and pink/orange at 84W. The power was varied using the 232 volume control. The 1W THD ratios were the lowest (the 10W data were very close, within 2-3dB), ranging from 0.0015% from 20Hz to 200Hz, then a steady climb to 0.04% at 20kHz. At 84W, THD ratios were fairly flat across the sweep at 0.2-0.3%.

THD ratio (unweighted) vs. output power at 1kHz into 4 and 8 ohms

The chart above shows THD ratios measured at the speaker-level outputs of the 232 as a function of output power for the analog line-level input for an 8-ohm load (blue/red for left/right) and a 4-ohm load (purple/green for left/right), with the volume set to maximum. The 8-ohm THD data is relatively constant at 0.002-0.003% from 50mW to the “knee” at just past 70W.  The 4-ohm THD data is also relatively constant at 0.005-0.006% from 50mW to the “knee” at roughly 130W. The 1% THD marks were hit at 90W and 150W into 8 and 4 ohms.

THD+N ratio (unweighted) vs. output power at 1kHz into 4 and 8 ohms

The chart above shows THD+N ratios measured at the speaker-level outputs of the 232 as a function of output power for the analog line level-input, for an 8-ohm load (blue/red for left/right) and a 4-ohm load (purple/green for left/right) with the volume set to maximum. The 8-ohm THD+N data ranges from 0.01% at 50mW down to between 0.002- 0.003% from 2W to the “knee” at just past 70W.  The 4-ohm THD+N data ranges from 0.02% at 50mW down to between 0.005- 0.006% from 2W to the “knee” at just roughly 130W.

THD ratio (unweighted) vs. frequency at 8, 4, and 2 ohms (left channel only)

The chart above shows THD ratios measured at the output of the 232 as a function of frequency into three different loads (8/4/2 ohms) for a constant input voltage that yields 20W at the output into 8 ohms (and roughly 40W into 4 ohms, and 80W into 2 ohms) for the analog line-level input. The 8-ohm load is the blue trace, the 4-ohm load the purple trace, and the 2-ohm load the pink trace. We find a roughly 5dB increase in THD from 8 to 4 to 2 ohms from 400Hz to 20kHz. At lower frequencies, the difference was smaller at 2-3dB. Even into 2 ohms, THD ratios ranged from 0.003% at 20Hz, climbing to 0.2% at 20kHz. A strong result, due to the 232’s robust power supply and exceedingly low output impedance.

THD ratio (unweighted) vs. frequency into 8 ohms and real speakers (left channel only)

The chart above shows THD ratios measured at the output of the 232 as a function of frequency into an 8-ohm load and two different speakers for a constant output voltage of 2.83Vrms (1W into 8 ohms) for the analog line-level input. The 8-ohm load is the blue trace, the purple plot is a two-way speaker (Focal Chora 806, measurements can be found here), and the pink plot is a three-way speaker (Paradigm Founder Series 100F, measurements can be found here). Generally, THD ratios into the real speakers were similar if not lower than those measured across the resistive dummy load. The largest differences were seen with the two-way speaker, which yielded THD ratios of 0.008% at 20Hz versus 0.0015% for the resistive load and three-way speaker, and 0.001% from 400Hz to 1kHz versus 0.002-0.003% for the resistive load and 3-way speaker. This is a very strong result. The 3-way speaker yielded the highest THD ratio at 20kHz, 0.06% versus 0.05% for the resistive load and 0.03% for the 2-way speaker. This is a very strong result, and once again, likely due to the 232’s robust power supply and exceedingly low output impedance.

IMD ratio (CCIF) vs. frequency into 8 ohms and real speakers (left channel only)

The chart above shows intermodulation distortion (IMD) ratios measured at the output of the 232 as a function of frequency into an 8-ohm load and two different speakers for a constant output voltage of 2.83Vrms (1W into 8 ohms) for the analog line-level input. Here the CCIF IMD method was used, where the primary frequency is swept from 20kHz (F1) down to 2.5kHz, and the secondary frequency (F2) is always 1kHz lower than the primary, with a 1:1 ratio. The CCIF IMD analysis results are the sum of the second (F1-F2 or 1kHz) and third modulation products (F1+1kHz, F2-1kHz). The 8-ohm load is the blue trace, the purple plot is a two-way speaker (Focal Chora 806, measurements can be found here), and the pink plot is a three-way speaker (Paradigm Founder Series 100F, measurements can be found here). We find that all three IMD traces are very close to one another, ranging from 0.0015% to 0.005%.

IMD ratio (SMPTE) vs. frequency into 8 ohms and real speakers (left channel only)

The chart above shows IMD ratios measured at the output of the 232 as a function of frequency into an 8-ohm load and two different speakers for a constant output voltage of 2.83Vrms (1W into 8 ohms) for the analog line-level input. Here, the SMPTE IMD method was used, where the primary frequency (F1) is swept from 250Hz down to 40Hz, and the secondary frequency (F2) is held at 7kHz with a 4:1 ratio. The SMPTE IMD analysis results consider the second (F2 ± F1) through the fifth (F2 ± 4xF1) modulation products. The 8-ohm load is the blue trace, the purple plot is a two-way speaker (Focal Chora 806, measurements can be found here), and the pink plot is a three-way speaker (Paradigm Founder Series 100F, measurements can be found here). At high frequencies, all three results are essentially identical at 0.002% from 500Hz to 1kHz. From 40Hz to 500Hz, the 3-way speaker yielded the highest IMD results at just under 0.02%, with the 2-way speaker at just under 0.01%, and the resistive load at 0.006%.

FFT spectrum – 1kHz (line-level input)

Shown above is the fast Fourier transform (FFT) for a 1kHz input sinewave stimulus, measured at the output across an 8-ohm load at 10W for the analog line-level input. We see that the signal’s even (2/4/6/8kHz/etc.) harmonics dominate with the peak at 2kHz at -90dBrA, or 0.003%, and subsequent peaks below -100dBrA, or 0.001%. The odd signal harmonics (3/5/7/9kHz/etc) can be seen at -110dBrA, or 0.0003%, and below. On the right side of the signal peak, we find power-supply-related noise peaks, with the second harmonic (120Hz) dominating at -115dBrA, or 0.0002%. Other noise peaks can be seen at and below the -120dBrA level.

FFT spectrum – 1kHz (digital input, 16/44.1 data at 0dBFS)

Shown above is the fast Fourier transform (FFT) for a 1kHz input sinewave stimulus, measured at the output across an 8-ohm load at 10W for the coaxial digital input, sampled at 16/44.1. Both the signal harmonics and power-supply related noise peaks are very similar in amplitude to the analog FFT above.

FFT spectrum – 1kHz (digital input, 24/96 data at 0dBFS)

Shown above is the fast Fourier transform (FFT) for a 1kHz input sinewave stimulus, measured at the output across an 8-ohm load at 10W for the coaxial digital input, sampled at 24/96. We see essentially the same result as with the 16/44.1 FFT above, but with a lower noise floor due to the increased bid depth.

FFT spectrum – 1kHz (digital input, 16/44.1 data at -90dBFS)

Shown above is the FFT for a 1kHz -90dBFS dithered 16/44.1 input sinewave stimulus at the coaxial digital input, measured at the output across an 8-ohm load. We see the 1kHz primary signal peak, at the correct amplitude, with no signal harmonics above the -135dBrA noise floor, and power-supply-related noise peaks at -130dBrA, or 0.00003%.

FFT spectrum – 1kHz (digital input, 24/96 data at -90dBFS)

Shown above is the FFT for a 1kHz -90dBFS dithered 24/96 input sinewave stimulus at the coaxial digital input, measured at the output across an 8-ohm load. We see the 1kHz primary signal peak, at the correct amplitude, with no obvious signal harmonics above the -145dBrA noise floor, and power-supply-related noise peaks at -130dBrA, or 0.00003%, down to -140dBrA, or 0.00001%.

FFT spectrum – 50Hz (line-level input)

Shown above is the FFT for a 50Hz input sinewave stimulus measured at the output across an 8-ohm load at 10W for the analog line-level input. The X axis is zoomed in from 40Hz to 1kHz, so that peaks from noise artifacts can be directly compared against peaks from the harmonics of the signal. The most predominant (non-signal) peak is the second (100Hz) signal harmonic at a low -95dBrA, or 0.002%. Other peaks (both signal harmonics and power-supply noise related harmonics) can be seen at -110dBrA, or 0.0003, and below.

Intermodulation distortion FFT (18kHz + 19kHz summed stimulus, line-level input)

Shown above is an FFT of the intermodulation distortion (IMD) products for an 18kHz + 19kHz summed sinewave stimulus tone measured at the output across an 8-ohm load at 10W for the analog line-level input. The input RMS values are set at -6.02dBrA so that, if summed for a mean frequency of 18.5kHz, would yield 10W (0dBrA) into 8 ohms at the output. We find that the second-order modulation product (i.e., the difference signal of 1kHz) is at -100dBRa, or 0.001%, while the third-order modulation products, at 17kHz and 20kHz are just below the -105dBrA, or 0.0006%, level.

Intermodulation distortion FFT (line-level input, APx 32 tone)

Shown above is the FFT of the speaker-level output of the 232 with the APx 32-tone signal applied to the analog input. The combined amplitude of the 32 tones is the 0dBrA reference, and corresponds to 10W into 8 ohms. The intermodulation products—i.e., the “grass” between the test tones—are distortion products from the amplifier and are at and below the -110dBrA, or 0.0003%, level.

Intermodulation distortion FFT (18kHz + 19kHz summed stimulus, coaxial digital input, 16/44.1)

Shown above is an FFT of the intermodulation distortion (IMD) products for an 18kHz + 19kHz summed sinewave stimulus tone measured at the output across an 8-ohm load at 10W for the digital coaxial input at 16/44.1 (-1dBFS). We find that the second-order modulation product (i.e., the difference signal of 1kHz) is at -100dBRa, or 0.001%, while the third-order modulation products, at 17kHz and 20kHz, are just below the -105dBrA, or 0.0006%, level.

Intermodulation distortion FFT (18kHz + 19kHz summed stimulus, coaxial digital input, 24/96)

Shown above is an FFT of the intermodulation distortion (IMD) products for an 18kHz + 19kHz summed sinewave stimulus tone measured at the output across an 8-ohm load at 10W for the digital coaxial input at 24/96 (-1dBFS). We find that the second-order modulation product (i.e., the difference signal of 1kHz) is at -100dBRa, or 0.001%, while the third-order modulation products, at 17kHz and 20kHz, are just below the -105dBrA, or 0.0006%, level.

Squarewave response (10kHz)

Above is the 10kHz squarewave response using the analog line-level input, at roughly 10W into 8 ohms. Due to limitations inherent to the Audio Precision APx555 B Series analyzer, this graph should not be used to infer or extrapolate the 232’s slew-rate performance. Rather, it should be seen as a qualitative representation of the 232’s mid-to-high bandwidth. An ideal squarewave can be represented as the sum of a sinewave and an infinite series of its odd-order harmonics (e.g., 10kHz + 30kHz + 50kHz + 70kHz . . .). A limited bandwidth will show only the sum of the lower-order harmonics, which may result in noticeable undershoot and/or overshoot, and softening of the edges. In this case, we find relatively clean corners, with some softening but no overshoot.

Damping factor vs. frequency (20Hz to 20kHz)

The final graph above is the damping factor as a function of frequency. We can see here a constant damping factor just under 1800 from 20Hz to 2kHz, then down to just under 1000 at 20kHz. This is an exceptional result for a medium-powered solid-state integrated amplifier.

Diego Estan
Electronics Measurement Specialist

Details

Parent Category: Products

Category: Amplifier Measurements

Created: 15 January 2026

Link: reviewed by Jason Thorpe on SoundStage! Ultra on January 15, 2026

General information

All measurements taken using an Audio Precision APx555 B Series analyzer.

The D‑80 was conditioned for 1 hour at 1/8th full rated power (~10W into 8 ohms) before any measurements were taken. All measurements were taken with both channels driven, using a 120V/20A dedicated circuit, unless otherwise stated.

The D‑80 is a two-channel amplifier with two balanced (XLR) inputs and three pairs of speaker level outputs: 4-, 8-, and 16-ohm taps. Unless otherwise stated, the 8-ohm taps were used for these measurements. An input of 520mVrms was required to achieve the reference 10W into 8 ohms.

Our typical input bandwidth filter setting of 10Hz-22.4kHz was used for all measurements except FFTs and THD versus frequency, where a bandwidth of 10Hz-90kHz was used. Frequency response measurements utilize a DC-to-1 MHz input bandwidth.

Published specifications vs. our primary measurements

The table below summarizes the measurements published by Audio Research for the D‑80 compared directly against our own. The published specifications are sourced from Audio Research’s website, either directly or from the manual available for download, or a combination thereof. Assume, unless otherwise stated, 10W into 8 ohms and a measurement input bandwidth of 10Hz to 22.4kHz. Our primary measurements revealed the following (unless specified, assume a 1kHz sinewave at 520mVrms at the input, 10W output, 8-ohm loading, 10Hz to 22.4kHz bandwidth):

Our primary measurements revealed the following using the balanced line-level analog input (unless specified, assume a 1kHz sinewave at 520mVrms, 10W output, 8-ohm loading, 10Hz to 22.4kHz bandwidth):

For the continuous dynamic power test, the D‑80 was able to sustain about 81W into 4 ohms (~3% THD) using an 80Hz tone for 500ms, alternating with a signal at -10dB of the peak (8.1W) for 5 seconds, for 5 continuous minutes without inducing a fault or the initiation of a protective circuit. This test is meant to simulate sporadic dynamic bass peaks in music and movies. During the test, the sides and top of the D‑80 were very hot to the touch.

Frequency response (8-ohm loading)

In our frequency-response (relative to 1kHz) plot above, measured across the speaker outputs at 10W into 8 ohms, the D‑80 exhibits a near-flat frequency response across the audioband (0/-0.25dB at 20Hz/20kHz). At 5Hz the D‑80 is at roughly -3dB, and the high frequency -3dB point is at 70kHz.

Phase response (8-ohm loading)

Above is the phase-response plot from 20Hz to 20kHz for the balanced line-level input, measured across the speaker outputs at 10W into 8 ohms. The D‑80 does not invert polarity and exhibits, at worst, only -20 degrees of phase shift at 20kHz.

RMS level vs. frequency vs. load impedance (1W, left channel only)

The chart above shows RMS level (relative to 0dBrA, which is 1W into 8 ohms or 2.83Vrms) as a function of frequency, for the analog line-level input swept from 10Hz to 100kHz. The blue plot is into an 8-ohm load, the purple is into a 4-ohm load, the pink plot is an actual speaker (Focal Chora 806, measurements can be found here), and the cyan plot is no load connected. The chart below . . .

. . . is the same but zoomed in to highlight differences. Here we find the maximum deviation between a 4-ohm load and no load to be around 2.2dB through most of the audioband. At 20kHz, the deviation is about 2.5dB. This is an indication of a very low damping factor, or high output impedance, endemic of most tube amplifiers. With a real speaker, the deviations from 20Hz to 20kHz were lower, but still within the potentially audible range, at roughly 1.6dB.

THD ratio (unweighted) vs. frequency vs. output power

The chart above shows THD ratios at the output into 8 ohms as a function of frequency for a sinewave stimulus at the analog line-level input. The blue plot is at 1W output into 8 ohms, purple at 10W, and pink is at the maximum achievable power (67W). THD ratios increase as power is increased. At 1W, THD ranges from 0.02% at lower frequencies to 0.1% at 20kHz. At 10W, we find THD ratios between 0.15% and 0.7% at 20kHz. And at 67W, THD ratios exceed 1%, ranging from about 1.5% to 5%.

THD ratio (unweighted) vs. output power at 1kHz into 4 and 8 ohms (8-ohm taps)

The chart above shows THD ratios measured at the output of the D‑80 as a function of output power for the analog line-level input for an 8-ohm load (blue/red) and a 4-ohm load (purple/green), for the 8-ohm taps. The 8-ohm data ranged from 0.005% at 50mW, steadily increasing to 1% at the maximum power output of 67W. Increasing the input voltage beyond this point only serves to increase THD while maintaining the same 67W. The 4-ohm data ranged from 0.015% at 50mW, steadily increasing to 2% at the maximum power output of 84W. Increasing the input voltage beyond this point only serves to increase THD while maintaining the same 84W.

THD+N ratio (unweighted) vs. output power at 1kHz into 4 and 8 ohms (8-ohm taps)

The chart above shows THD+N ratios measured at the output of the D‑80 as a function of output power for the analog line level-input, for an 8-ohm load (blue/red) and a 4-ohm load (purple/green), for the 8-ohm taps. The 8-ohm data ranged from 0.02% at 50mW, steadily increasing to 1% at the maximum power output of 67W. Increasing the input voltage beyond this point only serves to increase THD+N while maintaining the same 67W. The 4-ohm data ranged from 0.015% at 50mW, steadily increasing to 2% at the maximum power output of 84W. Increasing the input voltage beyond this point only serves to increase THD+N while maintaining the same 84W.

THD ratio (unweighted) vs. output power at 1kHz into 4 and 8 ohms (4-ohm taps)

The chart above shows THD ratios measured at the output of the D‑80 as a function of output power for the analog line-level input for an 8-ohm load (blue/red) and a 4-ohm load (purple/green), for the 4-ohm taps. The 8-ohm data ranged from 0.005% at 50mW, steadily increasing to roughly 1.5% at the maximum power output of just past 40W. Increasing the input voltage beyond this point only serves to increase THD while maintaining the same power. The 4-ohm data ranged from 0.02% at 50mW, steadily increasing to 1.5% at the maximum power output of just past 60W. Increasing the input voltage beyond this point only serves to increase THD while maintaining the same power.

THD+N ratio (unweighted) vs. output power at 1kHz into 4 and 8 ohms (4-ohm taps)

The chart above shows THD+N ratios measured at the output of the D‑80 as a function of output power for the analog line level-input, for an 8-ohm load (blue/red) and a 4-ohm load (purple/green), for the 4-ohm taps. The 8-ohm data ranged from 0.02% at 50mW, steadily increasing to roughly 1.5% at the maximum power output of just past 40W. Increasing the input voltage beyond this point only serves to increase THD+N while maintaining the same power. The 4-ohm data ranged from 0.03% at 50mW, steadily increasing to 1.5% at the maximum power output of just past 60W. Increasing the input voltage beyond this point only serves to increase THD+N while maintaining the same power.

THD ratio (unweighted) vs. frequency at 8, 4, and 2 ohms (left channel only)

The chart above shows THD ratios measured at the output of the D‑80 as a function of frequency into three different loads (8/4/2 ohms) for a constant input voltage that yields roughly 10W at the output into 8 ohms (blue), 20W into 4 ohms (purple), and 40W into 2 ohms (pink). The 8-ohm data ranged from 0.1-0.2% between 20Hz and 4kHz, then up to 0.7% at 20kHz. The 4-ohm THD data ranged from 0.5% from 20Hz to 200Hz, then steadily up to 2.5% at 20kHz. The 2-ohm data yielded THD ratios from 2% at 20Hz up to 8% at 20kHz. This shows that the D‑80 is stable into 2-ohms, but will exhibit very high THD ratios.

THD ratio (unweighted) vs. frequency into 8 ohms and real speakers (left channel only)

The chart above shows THD ratios measured at the output of the D‑80 as a function of frequency into an 8-ohm load and two different speakers for a constant output voltage of 2.83Vrms (1W into 8 ohms) for the analog line-level input. The 8-ohm load is the blue trace, the purple plot is a two-way speaker (Focal Chora 806, measurements can be found here), and the pink plot is a three-way speaker (Paradigm Founder Series 100F, measurements can be found here). At very low frequencies, the two-way speaker yielded the highest THD ratios (2%). In the all-important 300Hz to 5kHz range, THD ratios into all three loads were close, with the data into real speakers hovering above and below (+/-10dB) the 0.02-0.03% values seen for the resistive load. At the highest frequencies, the three-way speaker yielded the highest THD ratios (0.2% at 20kHz).

IMD ratio (CCIF) vs. frequency into 8 ohms and real speakers (left channel only)

The chart above shows intermodulation distortion (IMD) ratios measured at the output of the D‑80 as a function of frequency into an 8-ohm load and two different speakers for a constant output voltage of 2.83Vrms (1W into 8 ohms) for the analog line-level input. Here the CCIF IMD method was used, where the primary frequency is swept from 20kHz (F1) down to 2.5kHz, and the secondary frequency (F2) is always 1kHz lower than the primary, with a 1:1 ratio. The CCIF IMD analysis results are the sum of the second (F1-F2 or 1kHz) and third modulation products (F1+1kHz, F2-1kHz). The 8-ohm load is the blue trace, the purple plot is a two-way speaker (Focal Chora 806, measurements can be found here), and the pink plot is a three-way speaker (Paradigm Founder Series 100F, measurements can be found here). The IMD results into the resistive load are fairly consistent, from 0.03 to 0.05% across the sweep. The results were lower and higher for the real speakers, ranging from 0.02% to 0.07%.

IMD ratio (SMPTE) vs. frequency into 8 ohms and real speakers (left channel only)

The chart above shows IMD ratios measured at the output of the D‑80 as a function of frequency into an 8-ohm load and two different speakers for a constant output voltage of 2.83Vrms (1W into 8 ohms) for the analog line-level input. Here, the SMPTE IMD method was used, where the primary frequency (F1) is swept from 250Hz down to 40Hz, and the secondary frequency (F2) is held at 7kHz with a 4:1 ratio. The SMPTE IMD analysis results consider the second (F2 ± F1) through the fifth (F2 ± 4xF1) modulation products. The 8-ohm load is the blue trace, the purple plot is a two-way speaker (Focal Chora 806, measurements can be found here), and the pink plot is a three-way speaker (Paradigm Founder Series 100F, measurements can be found here). The IMD results into the resistive load remained constant at 0.1% across the weep. The results were lower and higher for the real speakers, ranging from 0.05% to nearly 0.2%.

FFT spectrum – 1kHz (line-level input)

Shown above is the fast Fourier transform (FFT) for a 1kHz input sinewave stimulus, measured at the output across an 8-ohm load at 10W for the balanced analog line-level input. We see that the signal’s second (2kHz), third (3kHz), and fifth (5kHz) harmonics dominate at -60dBrA (2/3kHz) and -70dBrA (5kHz), or 0.1% and 0.03%. Other signal harmonics can be seen from -90dBrA (0.003%) to below -120dBrA (0.0001%). There are power-supply noise-related harmonics throughout the FFT, at -100dBrA, or 0.001%, and below.

FFT spectrum – 50Hz (line-level input)

Shown above is the FFT for a 50Hz input sinewave stimulus measured at the output across an 8-ohm load at 10W for the balanced analog line-level input. The X axis is zoomed in from 40Hz to 1kHz, so that peaks from noise artifacts can be directly compared against peaks from the harmonics of the signal. The most dominant (non-signal) peaks are again the signal’s second (100Hz), third (150Hz), and fifth (250Hz) harmonics at -60dBrA (100/150kHz) and -70dBrA (250Hz), or 0.1% and 0.03%. There are power-supply noise-related harmonics throughout the FFT, at -100dBrA, or 0.001%, and below.

Intermodulation distortion FFT (18kHz + 19kHz summed stimulus, line-level input)

Shown above is an FFT of the intermodulation distortion (IMD) products for an 18kHz + 19kHz summed sinewave stimulus tone measured at the output across an 8-ohm load at 10W for the balanced analog line-level input. The input RMS values were set at -6.02dBrA so that, if summed for a mean frequency of 18.5kHz, would yield 10W (0dBrA) into 8 ohms at the output. We find that the second-order modulation product (i.e., the difference signal of 1kHz) is at the -65dBrA (0.2%) level, while the third-order modulation products, at 17kHz and 20kHz, are at the same level.

Intermodulation distortion FFT (line-level input, APx 32 tone)

Shown above is the FFT of the speaker-level output of the D‑80 with the APx 32-tone signal applied to the input. The combined amplitude of the 32 tones is the 0dBrA reference, and corresponds to 10W into 8 ohms. The intermodulation products—i.e., the “grass” between the test tones—are distortion products from the amplifier and are at the -90dBrA, or 0.003%, level.

Square-wave response (10kHz)

Above is the 10kHz squarewave response using the balanced analog line-level input, at roughly 10W into 8 ohms. Due to limitations inherent to the Audio Precision APx555 B Series analyzer, this graph should not be used to infer or extrapolate the D‑80’s slew-rate performance. Rather, it should be seen as a qualitative representation of the D‑80’s relatively wide bandwidth. An ideal squarewave can be represented as the sum of a sinewave and an infinite series of its odd-order harmonics (e.g., 10kHz + 30kHz + 50kHz + 70kHz . . .). A limited bandwidth will show only the sum of the lower-order harmonics, which may result in noticeable undershoot and/or overshoot, and softening of the edges. In this case, we see a reasonably clean result, with mild ringing in the plateaus.

Damping factor vs. frequency (20Hz to 20kHz)

The final graph above is the damping factor as a function of frequency. We find very low damping-factor values, from 6-7 from 20Hz to 2kHz. This is a very poor damping factor result, but typical for tube amps.

Diego Estan
Electronics Measurement Specialist

Details

Parent Category: Products

Category: Amplifier Measurements

Created: 01 January 2026

Link: reviewed by Roger Kanno on SoundStage! Simplifi on January 1, 2026

General Information

All measurements taken using an Audio Precision APx555 B Series analyzer.

The Line Majik DSM was conditioned for 1 hour at 1/8th full rated power (~10W into 8 ohms) before any measurements were taken. All measurements were taken with both channels driven, using a 120V/20A dedicated circuit, unless otherwise stated.

The Majik DSM offers two line-level analog inputs (RCA), moving-magnet (MC) and moving-coil (MC) phono inputs (RCA), two digital S/PDIF inputs (RCA coaxial and TosLink optical), and other network connections for streaming. In terms of outputs, there are line-level subwoofer and pre-outs (RCA), and a pair of speaker level outputs. Also included is a ¼″ TRS headphone output on the front panel. For the purposes of these measurements, the following inputs were evaluated: coaxial digital (RCA) and the analog line-level and phono MM and MC (RCA) inputs.

Most measurements were made with a 2Vrms line-level analog input or 0dBFS digital input. The signal-to-noise (SNR) measurements were made with the same input signal values but with the volume set to achieve the output power of 74W (into 8 ohms) for 1% THD. For comparison, on the analog input, a SNR measurement was also made with the volume at maximum, but with a lower input signal to achieve the same 74W.

Based on the accuracy and repeatability at various volume levels of the left/right channel matching (see table below), the Majik DSM volume control is operating in the digital domain. Consequently, all analog signals are digitized (sampled at 24/192) at the Majik DSM’s inputs so the unit may apply volume and EQ functions. The volume control offers a total range from -65dB to +34dB (line-level inputs, speaker level outputs) using 100 increments of 1dB.

Because the Majik DSM is a digital amplifier technology that exhibits considerable noise above 20kHz (see FFTs below), our typical input bandwidth filter setting of 10Hz-90kHz was necessarily changed to 10Hz-22.4kHz for all measurements, except for frequency response and for FFTs. In addition, THD versus frequency sweeps were limited to 6kHz to adequately capture the second and third signal harmonics with the restricted-bandwidth setting.

Volume-control accuracy (measured at speaker outputs): left-right channel tracking

Published specifications vs. our primary measurements

The table below summarizes the measurements published by Linn for the Majik DSM compared directly against our own. The published specifications are sourced from Linn’s website, either directly or from the manual available for download, or a combination thereof. With the exception of frequency response, where the Audio Precision bandwidth was extended to 1MHz, assume, unless otherwise stated, 10W into 8ohms and a measurement input bandwidth of 10Hz to 22.4kHz, and the worst-case measured result between the left and right channels.

Our primary measurements revealed the following using the line-level analog input and digital coaxial input (unless specified, assume a 1kHz sinewave at 2Vrms or 0dBFS, 10W output, 8-ohm loading, 10Hz to 22.4kHz bandwidth):

For the continuous dynamic power test, the Majik DSM was able to sustain 148W into 4 ohms (~4% THD) using an 80Hz tone for 500ms, alternating with a signal at -10dB of the peak (14.8W) for 5 seconds, for 5 minutes without inducing the fault protection circuit. This test is meant to simulate sporadic dynamic bass peaks in music and movies. During the test, the top of the Majik DSM was slightly warm to the touch.

Our primary measurements revealed the following using the phono-level input, MM configuration (unless specified, assume a 1kHz 5mVrms sinewave input, 10W output, 8-ohm loading, 10Hz to 22.4kHz bandwidth):

Our primary measurements revealed the following using the phono-level input, MC configuration (unless specified, assume a 1kHz 0.5mVrms sinewave input, 10W output, 8-ohm loading, 10Hz to 22.4kHz bandwidth):

Our primary measurements revealed the following using the analog input at the headphone output (unless specified, assume a 1kHz sinewave, 2Vrms input/output, 300 ohms loading, 10Hz to 22.4kHz bandwidth):

Frequency response (8-ohm loading, line-level input)

In our frequency response plots above (relative to 1kHz), measured across the speaker outputs at 10W into 8 ohms, the Majik DSM is near flat within the audioband (20Hz to 20kHz, 0/-0.2dB). The -3dB point is at roughly 55kHz, with sharp high-frequency attenuation. Due to either noise or excessive DC leakage, we could not measure the Majik DSM without a low-pass filter (10Hz) on the analyzer’s inputs. This is why the plot is limited to 10Hz (and not 5Hz). In the graph above and most of the graphs below, only a single trace may be visible. This is because the left channel (blue or purple trace) is performing identically to the right channel (red or green trace), and so perfectly overlap, indicating that the two channels are ideally matched.

Frequency response (8-ohm loading, line-level input with subwoofer output)

The chart above shows the frequency response (relative to 1kHz) measured across the speaker outputs at 10W into 8 ohms, as well as the line-level sub-out frequency response (relative to 20Hz). The subwoofer was engaged in the settings for these measurements, with the cut-off frequency set to 80Hz. The Bass Redirect setting was engaged, which applies a low-pass second order filter to the line-level sub-outs, and a mirror high-pass filter to the main speaker outputs. We see that both traces merge at 80Hz at -6dB, as expected.

Phase response (8-ohm loading, line-level input)

Above are the phase response plots from 20Hz to 20kHz for the line-level input, measured across the speaker outputs at 10W into 8 ohms. The Majik DSM digitizes all incoming analog signals at 24/192, subsequently, true phase delay will be significant as it includes the timing delay associated with the ADC process. Here we see roughly -500000 degrees at 20kHz. Below, is . . .

. . . a phase plot that only shows the excess phase (timing delays removed). Here we see +20 degrees at 20Hz (which should be ignored because the low-pass filter on the analyzer inputs had to be engaged), and +40 degrees at 20kHz.

Frequency response (8-ohm loading, MM phono input)

The chart above shows the frequency response (relative to 1kHz) for the MM phono input. What is shown is the deviation from the RIAA curve, where the input signal sweep is EQ’d with an inverted RIAA curve supplied by Audio Precision (i.e., zero deviation would yield a flat line at 0dB). We see a very flat response from 20Hz to 3kHz (indicative of RIAA EQ applied in the digital domain), followed by a steep rise in response (+1dB at 20kHz), peaking at 45kHz (+4dB).

Frequency response (8-ohm loading, MC phono input)

The chart above shows the frequency response for the MC phono input. We see a very flat response across the audioband (0dB at 20Hz, -0.2dB at 20kHz).

Phase response (8-ohm loading, MM input, excess)

Above is the excess phase response plot from 20Hz to 20kHz for the MM phono input, measured across the speaker outputs at 10W into 8 ohms. The Majik DSM does not invert polarity. For the phono input, since the RIAA equalization curve must be implemented, which ranges from +19.9dB (20Hz) to -32.6dB (90kHz), phase shift at the output is inevitable. Here we find a worst case of about +100 degrees at 20Hz and -5 degrees at 6-8kHz.

Phase response (8-ohm loading, MC input, excess)

Above is the excess phase response plot from 20Hz to 20kHz for the MC phono input, measured across the speaker outputs at 10W into 8 ohms. We find the same result as with the MM input above.

Frequency response vs. input type (8-ohm loading, left channel only)

The chart above shows the Majik DSM’s frequency response (relative to 1kHz) as a function of input type measured across the speaker outputs at 10W into 8 ohms. The two green traces are the same analog input data from the speaker-level frequency-response graph above. The blue and red traces are for a 16-bit/44.1kHz dithered digital input signal from 5Hz to 22kHz using the coaxial input, the purple and green traces are for a 24/96 dithered digital input signal from 5Hz to 48kHz, and the pink and orange traces are for a 24/192 dithered digital input signal. The -3dB points are roughly: 21kHz for the 16/44.1 data, 40kHz for the 24/96, and 55kHz for the 24/192 data. The analog plots follow the 24/192 plots as expected, because analog signals are sampled at 24/192.

Digital linearity (16/44.1 and 24/96 data)

The chart above shows the results of a linearity test for the coaxial digital input for both 16/44.1 (blue/red) and 24/96 (purple/green) input data, measured at the line-level pre-outputs of the Majik DSM, where 0dBFS was set to yield 1Vrms. For this test, the digital input is swept with a dithered 1kHz input signal from -120dBFS to 0dBFS, and the output is analyzed by the APx555. The ideal response would be a straight flat line at 0dB. Both data were essentially perfect as of -100dBFS down to 0dBFS. The 24/96 data were at +1dB at -120dBFS, while the 16/44.1 data were +2/3dB at -120dBFS.

Impulse response (24/44.1 data)

The graph above shows the impulse response for a looped 24/44.1 test file that moves from digital silence to full 0dBFS (all “1”s) for one sample period then back to digital silence, measured at the line-level pre-outs of the Majik DSM. We find a typical symmetrical sinc-function response.

J-Test (coaxial)

The chart above shows the results of the J-Test test for the coaxial digital input measured at the line-level pre-outputs of the Majik DSM where 0dBFS is set to 1Vrms. J-Test was developed by Julian Dunn the 1990s. It is a test signal—specifically, a -3dBFS undithered 12kHz squarewave sampled (in this case) at 48kHz (24bit). Since even the first odd harmonic (i.e., 36kHz) of the 12kHz squarewave is removed by the bandwidth limitation of the sampling rate, we are left with a 12kHz sinewave (the main peak). In addition, an undithered 250Hz squarewave at -144dBFS is mixed with the signal. This test file causes the 22 least-significant bits to constantly toggle, which produces strong jitter spectral components at the 250Hz rate and its odd harmonics. The test file shows how susceptible the DAC and delivery interface are to jitter, which would manifest as peaks above the noise floor at 500Hz intervals (e.g., 250Hz, 750Hz, 1250Hz, etc.). Note that the alternating peaks are in the test file itself, but at levels of -144dBrA and below. The test file can also be used in conjunction with artificially injected sinewave jitter by the Audio Precision, to show how well the DAC rejects jitter.

Here we see a relatively strong J-Ttest result. While several peaks can be seen in the audioband, they are very low in amplitude and range from -135dBFS down to -150dBFS. This is an indication that the Majik DSM DAC may have strong jitter immunity.

J-Test (optical)

The chart above shows the results of the J-Test test for the optical digital input measured at the line-level pre-outputs of the Majik DSM. The optical input yielded essentially the same results compared to the coaxial input.

J-Test (coaxial, 100ns jitter)

The chart above shows the results of the J-Test test for the coaxial digital input measured at the line-level output of the Majik DSM, with an additional 100ns of 2kHz sinewave jitter injected by the APx555. The telltale peaks at 10kHz and 12kHz cannot be seen, indicating strong jitter rejection. The optical input yielded the same result.

Wideband FFT spectrum of white noise and 19.1kHz sine-wave tone (coaxial input)

The chart above shows a fast Fourier transform (FFT) of the Majik DSM’s line-level pre-outputs with white noise at -4dBFS (blue/red) and a 19.1 kHz sinewave at 0dBFS fed to the coaxial digital input, sampled at 16/44.1. The steep roll-off around 20kHz in the white-noise spectrum shows brickwall-type filtering. There are no low-level aliased image peaks within the audioband. The primary aliasing signal at 25kHz is highly suppressed at -140dBrA, while the second and third distortion harmonics (38.2, 57.3kHz) of the 19.1kHz signal are at -105 and -120dBFS.

RMS level vs. frequency vs. load impedance (1W, left channel only)

The chart above shows RMS level (relative to 0dBrA, which is 1W into 8 ohms or 2.83Vrms) as a function of frequency, for the analog line-level input swept from 10Hz to 50kHz. The blue plot is into an 8-ohm load, the purple is into a 4-ohm load, the pink plot is an actual speaker (Focal Chora 806, measurements can be found here), and the cyan plot is no load connected. The chart below . . .

. . . is the same but zoomed in to highlight differences. Here we see that the deviations between no load and 4 ohms are roughly 0.2dB. With a real speaker load, deviations measured lower, at roughly 0.1dB. At frequencies above 3-4kHz, there appears to be some sort of active compensation occurring at the outputs (the no load and 4-ohm load plots cross over at 6kHz, which would imply a negative output impedance).

THD ratio (unweighted) vs. frequency vs. output power

The chart above shows THD ratios at the speaker-level outputs into 8 ohms as a function of frequency for a sinewave stimulus at the analog line-level input. The blue and red plots are for the left and right channels at 1W output into 8 ohms, purple/green at 10W, and pink/orange at 65W. The power was varied using the Majik DSM’s volume control. The 1W THD ratios were the lowest, ranging from 0.0005% from 20Hz to 1kHz, then up to 0.002% at 20kHz. The 10W THD ratios were slightly higher ranging from 0.0005% to 0.004%. At 65W, THD ratios ranged from 0.0005% at lower frequencies, up to roughly 0.005-0.01% from 150Hz to 20kHz.

THD ratio (unweighted) vs. frequency at 10W (phono input, MM and MC)

The chart above shows THD ratios as a function of frequency plots for the MM (blue/red) and MC (purple/green) phono inputs measured across an 8-ohm load at 10W. For this test, the input sweep was EQ’d with an inverted RIAA curve. The THD values for the MM configuration vary from around 0.03% (20Hz) down to 0.002% (2/3kHz left channel), then up to 0.005% at 20kHz. The THD values for the MC configuration vary from around 0.01% (20Hz) down to 0.002% (2/3kHz), then up to 0.005% at 20kHz. It should be noted that often the limiting factor in THD measurements for phono inputs is the higher noise floor. The analyzer cannot assign a THD ratio for a signal harmonic peak it cannot see above the noise floor, and therefore the THD ratio is assigned the value of the noise floor relative to the signal.

THD ratio (unweighted) vs. output power at 1kHz into 4 and 8 ohms

The chart above shows THD ratios measured at the speaker-level outputs of the Majik DSM as a function of output power for the analog line-level input for an 8-ohm load (blue/red for left/right) and a 4-ohm load (purple/green for left/right), with the volume set to maximum. THD ratios into 4 and 8 ohms are close (with 3-4dB below 10W). For the 8-ohm load, they range from 0.015% at 50mW, down to just above 0.001% in the 10 to 50W range. The “knee” into 8 ohms can be found just past 55W, with the 1% THD mark hit at 74W. For the 4-ohm load, THD ratios range from 0.02% at 50mW, down to 0.002% at 10W, then up to 0.003% up to the “knee,” just past 100W, with the 1% THD mark hit at 136W.

THD+N ratio (unweighted) vs. output power at 1kHz into 4 and 8 ohms

The chart above shows THD+N ratios measured at the speaker-level outputs of the Majik DSM as a function of output power for the analog line-level input for an 8-ohm load (blue/red for left/right) and a 4-ohm load (purple/green for left/right). THD+N ratios into 4 and 8 ohms are close (with 3-4dB). They range from 0.1-0.2% at 50mW, down to 0.005-0.006% at the “knees.”

THD ratio (unweighted) vs. frequency at 8, 4, and 2 ohms (left channel only)

The chart above shows THD ratios measured at the output of the Majik DSM as a function of frequency into three different loads (8/4/2 ohms) for a constant input voltage that yields 10W at the output into 8 ohms (and roughly 20W into 4 ohms, and 40W into 2 ohms) for the analog line-level input. The 8-ohm load is the blue trace and the 4-ohm load the purple trace. We find a roughly 5-10dB increase in THD from 8 to 4 to 2 ohms. These ranged from 0.0005% from 20Hz to 300Hz, then up to 0.004% at 20kHz for the 8-ohm load. The 4-ohm load ranged from 0.0006% at 20-30Hz up to 0.005% at 20kHz. The 2-ohm load ranged from 0.001% at 20Hz up to 0.006% from 1-3kHz, then up to 0.008% at 20kHz.

THD ratio (unweighted) vs. frequency into 8 ohms and real speakers (left channel only)

The chart above shows THD ratios measured at the output of the Majik DSM as a function of frequency into an 8-ohm load and two different speakers for a constant output voltage of 2.83Vrms (1W into 8 ohms) for the analog line-level input. The 8-ohm load is the blue trace, the purple plot is a two-way speaker (Focal Chora 806, measurements can be found here), and the pink plot is a thee-way speaker (Paradigm Founder Series 100F, measurements can be found here). Generally, THD ratios into the real speakers were much higher than those measured across the resistive dummy load, from 20Hz to 1kHz. The differences ranged from 0.1% at 20Hz for the two-way speaker (0.01% for the three-way speaker) versus 0.0005% for the resistive load, and 0.004% at 20kHz into the three-way speaker versus 0.002% for the resistive load. Between 1kHz and 3kHz, all three THD traces were very close, around the 0.0006-0.0007% mark.

IMD ratio (CCIF) vs. frequency into 8 ohms and real speakers (left channel only)

The chart above shows intermodulation distortion (IMD) ratios measured at the output of the Majik DSM as a function of frequency into an 8-ohm load and two different speakers for a constant output voltage of 2.83Vrms (1W into 8 ohms) for the analog line-level input. Here the CCIF IMD method was used, where the primary frequency is swept from 20kHz (F1) down to 2.5kHz, and the secondary frequency (F2) is always 1kHz lower than the primary, with a 1:1 ratio. The CCIF IMD analysis results are the sum of the second (F1-F2 or 1kHz) and third modulation products (F1+1kHz, F2-1kHz). The 8-ohm load is the blue trace, the purple plot is a two-way speaker (Focal Chora 806, measurements can be found here), and the pink plot is a three-way speaker (Paradigm Founder Series 100F, measurements can be found here). We find that all three IMD traces are close to one another, ranging from 0.001-0.002% at 2.5kHz, up to a peak of 0.05% at around 15kHz.

IMD ratio (SMPTE) vs. frequency into 8 ohms and real speakers (left channel only)

The chart above shows IMD ratios measured at the output of the Majik as a function of frequency into an 8-ohm load and two different speakers for a constant output voltage of 2.83Vrms (1W into 8 ohms) for the analog line-level input. Here, the SMPTE IMD method was used, where the primary frequency (F1) is swept from 250Hz down to 40Hz, and the secondary frequency (F2) is held at 7kHz with a 4:1 ratio. The SMPTE IMD analysis results consider the second (F2 ± F1) through fifth (F2 ± 4xF1) modulation products. The 8-ohm load is the blue trace, the purple plot is a two-way speaker (Focal Chora 806, measurements can be found here), and the pink plot is a three-way speaker (Paradigm Founder Series 100F, measurements can be found here). We find very similar IMD ratios into all three loads; a flat 0.003% across the sweep.

FFT spectrum – 1kHz (line-level input)

Shown above is the fast Fourier transform (FFT) for a 1kHz input sinewave stimulus, measured at the output across an 8-ohm load at 10W for the analog line-level input. We see that the signal’s second (2kHz) and third (3kHz) harmonics dominate at a -110/-105dBrA, or 0.0003/0.0006%. There are subsequent signal harmonics visible at and below the -120dBrA, or 0.0001%, level. On the right side of the signal peak, we find no power-supply-related noise peaks above the -130 to -140dBrA noise floor. We also see a rise in the noise floor above 20kHz, characteristic of class-D amps.

FFT spectrum – 1kHz (MM phono input)

Shown above is the fast Fourier transform (FFT) for a 1kHz input sinewave stimulus, measured at the output across an 8-ohm load at 10W for the phono MM input. We see that the signal’s second (2kHz) and third (3kHz) harmonics dominate at a -110/-105dBrA, or 0.0003/0.0006%, the same as with the line-level FFT above. On the right side of the signal peak, we find two main power-supply-related noise peaks: the primary (60Hz) at -80dBrA, or 0.01%, and the third harmonic (180Hz) at -85dBrA, or 0.006%.

FFT spectrum – 1kHz (MC phono input)

Shown above is the fast Fourier transform (FFT) for a 1kHz input sinewave stimulus, measured at the output across an 8-ohm load at 10W for the phono MC input. We see that the signal’s second (2kHz) harmonic can be seen amongst the power-supply-related noise peaks at -100dBrA, or 0.001%. On the right side of the signal peak, we find the two most significant main power-supply related noise peaks at 60Hz (-60dBrA, or 0.1%) and 180Hz (-65dBrA, or 0.06%). A multitude of subsequent power-supply-related noise harmonics can be seen at and below -80dBrA, or 0.01%.

FFT spectrum – 1kHz (digital input, 16/44.1 data at 0dBFS)

Shown above is the fast Fourier transform (FFT) for a 1kHz input sinewave stimulus, measured at the output across an 8-ohm load at 10W for the coaxial digital input, sampled at 16/44.1. We see that the signal’s second (2kHz) and third (3kHz) harmonics dominate at a -110/-105dBrA, or 0.0003/0.0006%.  Subsequent harmonics can be seen at and below the -120dBrA, or 0.0001%, level. No visible power-supply-related noise peaks can be seen above the -135dBrA noise floor.

FFT spectrum – 1kHz (digital input, 24/96 data at 0dBFS)

Shown above is the fast Fourier transform (FFT) for a 1kHz input sinewave stimulus, measured at the output across an 8-ohm load at 10W for the coaxial digital input, sampled at 24/96. We see essentially the same result as with the 16/44.1 FFT above, but with a lower noise floor due to the increased bid depth.

FFT spectrum – 1kHz (digital input, 16/44.1 data at -90dBFS)

Shown above is the FFT for a 1kHz -90dBFS dithered 16/44.1 input sinewave stimulus at the coaxial digital input, measured at the output across an 8-ohm load. We see the 1kHz primary signal peak, at the correct amplitude, with the second (2kHz) signal harmonic just barely noticeable above the -135dBrA noise floor.

FFT spectrum – 1kHz (digital input, 24/96 data at -90dBFS)

Shown above is the FFT for a 1kHz -90dBFS dithered 24/96 input sinewave stimulus at the coaxial digital input, measured at the output across an 8-ohm load. We see the 1kHz primary signal peak, at the correct amplitude, and signal harmonics between -120 and -140dBrA (0.0001-0.00001%).

FFT spectrum – 50Hz (line-level input)

Shown above is the FFT for a 50Hz input sinewave stimulus measured at the output across an 8-ohm load at 10W for the analog line-level input. The X axis is zoomed in from 40Hz to 1kHz, so that peaks from noise artifacts can be directly compared against peaks from the harmonics of the signal. The most predominant (non-signal) peak is the second (100Hz) signal harmonic at -100dBrA, or 0.001%. Other signal harmonics peaks can be seen at -110dBrA and below.

FFT spectrum – 50Hz (MM phono input)

Shown above is the FFT for a 50Hz input sinewave stimulus measured at the output across an 8-ohm load at 10W for the MM phono input. The X axis is zoomed in from 40 Hz to 1kHz, so that peaks from noise artifacts can be directly compared against peaks from the harmonics of the signal. The most predominant (non-signal) peaks are the 60Hz fundamental power-supply noise peak and its third (180Hz) harmonic at -80/-85dBrA, or 0.01/0.006%. The highest signal harmonic peak is at 100Hz, at -90dBrA, or 0.003%.  

FFT spectrum – 50Hz (MC phono input)

Shown above is the FFT for a 50Hz input sinewave stimulus measured at the output across an 8-ohm load at 10W for the MC phono input. The X axis is zoomed in from 40 Hz to 1kHz, so that peaks from noise artifacts can be directly compared against peaks from the harmonics of the signal. The most predominant (non-signal) peaks are the 60Hz fundamental power-supply noise peak and its third (180Hz) harmonic at -60/-65dBrA, or 0.1/0.06%. The highest signal harmonic is at 100Hz, at -70dBrA, or 0.03%.

Intermodulation distortion FFT (18kHz + 19kHz summed stimulus, line-level input)

Shown above is an FFT of the intermodulation distortion (IMD) products for an 18kHz + 19kHz summed sinewave stimulus tone measured at the output across an 8-ohm load at 10W for the analog line-level input. For this test, the input RMS values are set at -6.02dBrA so that, if summed for a mean frequency of 18.5kHz, would yield 10W (0dBrA) into 8 ohms at the output. We find that the second-order modulation product (i.e., the difference signal of 1kHz) is at -120dBrA, or 0.0001%, while the third-order modulation products, at 17kHz and 20kHz, are at the -95dBrA, or 0.002%, level.

Intermodulation distortion FFT (line-level input, APx 32 tone)

Shown above is the FFT of the speaker-level output of the Majik DSM with the APx 32-tone signal applied to the analog input. The combined amplitude of the 32 tones is the 0dBrA reference and corresponds to 10W into 8 ohms. The intermodulation products—i.e., the “grass” between the test tones—are distortion products from the amplifier and are at and below the -125dBrA level.

Intermodulation distortion FFT (18kHz + 19kHz summed stimulus, coaxial digital input, 16/44.1)

Shown above is an FFT of the intermodulation distoriton (IMD) products for an 18kHz + 19kHz summed sinewave stimulus tone measured at the output across an 8-ohm load at 10W for the digital coaxial input at 16/44.1 (-1dBFS). We find that the second-order modulation product (i.e., the difference signal of 1kHz) is at -120dBrA, or 0.0001%, while the third-order modulation products, at 17kHz and 20kHz, are at the -95dBrA, or 0.002%, level.

Intermodulation distortion FFT (18kHz + 19kHz summed stimulus, coaxial digital input, 24/96)

Shown above is an FFT of the intermodulation distortion (IMD) products for an 18kHz + 19kHz summed sinewave stimulus tone measured at the output across an 8-ohm load at 10W for the digital coaxial input at 24/96 (-1dBFS).We find that the second-order modulation product (i.e., the difference signal of 1kHz) is at -120dBrA, or 0.0001%, while the third-order modulation products, at 17kHz and 20kHz, are at the -95dBrA, or 0.002%, level.

Intermodulation distortion FFT (18kHz + 19kHz summed stimulus, MM phono input)

Shown above is an FFT of the intermodulation distortion (IMD) products for an 18kHz + 19kHz summed sinewave stimulus tone measured at the output across an 8-ohm load at 10W for the MM phono input. We find that the second-order modulation product (i.e., the difference signal of 1kHz) is at -100dBrA, or 0.001%, while the third-order modulation products, at 17kHz and 20kHz, are at -90dBrA, or 0.003%.

Intermodulation distortion FFT (18kHz + 19kHz summed stimulus, MC phono input)

Shown above is an FFT of the intermodulation distortion (IMD) products for an 18kHz + 19kHz summed sinewave stimulus tone measured at the output across an 8-ohm load at 10W for the MC phono input. We find that the second-order modulation product (i.e., the difference signal of 1kHz) is at -90dBrA, or 0.003%, while the third-order modulation products, at 17kHz and 20kHz, are at -95dBrA, or 0.002%.

Squarewave response (10kHz)

Above is the 10kHz squarewave response using the analog line-level input, at roughly 10W into 8 ohms. Due to limitations inherent to the Audio Precision APx555 B Series analyzer, this graph should not be used to infer or extrapolate the Majik DSM’s slew-rate performance. Rather, it should be seen as a qualitative representation of the Majik DSM’s mid-tier bandwidth. An ideal squarewave can be represented as the sum of a sinewave and an infinite series of its odd-order harmonics (e.g., 10kHz + 30kHz + 50kHz + 70kHz . . .). A limited bandwidth will show only the sum of the lower-order harmonics, which may result in noticeable undershoot and/or overshoot, and softening of the edges. In this case, we find very soft/rounded corners, and the 600kHz oscillator modulating the square wave.

Squarewave response (1kHz)

Above is the 1kHz squarewave response using the analog line-level input, with a 250kHz bandwidth restriction on the analyzer’s inputs to filter out the 600kHz oscillator. Here we see a relatively clean response with some overshoot and ringing in the corners.

FFT spectrum of 400kHz switching frequency relative to a 1kHz tone

The Majik DSM’s amplifier relies on a switching oscillator to convert the input signal to a pulse-width-modulated (PWM) squarewave (on/off) signal before sending the signal through a low-pass filter to generate an output signal. The Majik DSM oscillator switches at a rate of about 600kHz, and this graph plots a wide bandwidth FFT spectrum of the amplifier’s output at 10W into 8 ohms as it’s fed a 1kHz sinewave. We can see that the 600kHz peak is quite evident, and at -35dBrA. There is also a peak at 1.2MHz (the second harmonic of the 600kHz peak), at -70dBrA. Those three peaks—the fundamental and its second harmonic—are direct results of the switching oscillators in the Majik DSM amp modules. The noise around those very-high-frequency signals are in the signal, but all that noise is far above the audioband—and therefore inaudible—and so high in frequency that any loudspeaker the amplifier is driving should filter it all out anyway.

Damping factor vs. frequency (20Hz to 20kHz)

The final graph above is the damping factor as a function of frequency. We can see here a constant damping factor of between 100 and 200 up to 2kHz. Beyond this point, there appears to be some sort of active compensation occurring at the outputs (a negative output impedance was measured, which is not possible).

Diego Estan
Electronics Measurement Specialist

Details

Parent Category: Products

Category: Amplifier Measurements

Created: 01 November 2025

Link: reviewed by Jason Thorpe on SoundStage! Ultra on November 1, 2025

General Information

All measurements taken using an Audio Precision APx555 B Series analyzer.

The VinnieRoss Brama was conditioned for 1 hour at 1/8th full rated power (~25W into 8 ohms) before any measurements were taken. All measurements were taken with both channels driven, using a 120V/20A dedicated circuit, unless otherwise stated.

The Brama offers five pairs of line-level balanced analog inputs (XLR only), one pair of left/right fixed line-level outputs (XLR), and two sets of speaker-level outputs. The Brama has three gain settings (low/medium/high at 22/28/34dB), unless otherwise stated, the medium setting was used.

Most measurements were made with a 2Vrms line-level analog input. The signal-to-noise (SNR) measurements were made with the default input signal values but with the volume set to achieve the achievable output power of 200W into 8 ohms. For comparison, an SNR measurement was also made with the volume at maximum.

Based on the accuracy and randomness of the left/right volume channel matching (see table below), the Brama volume control is operating in the analog domain. The Brama overall volume range is from -32dB to +27dB (balanced line-level input, speaker output).

Our typical input bandwidth filter setting of 10Hz-22.4kHz was used for all measurements except FFTs and THD versus frequency, where a bandwidth of 10Hz-90kHz was used. Frequency response measurements utilize a DC to 1MHz input bandwidth.

Volume-control accuracy (measured at speaker outputs): left-right channel tracking

Published specifications vs. our primary measurements

The table below summarizes the measurements published by VinnieRossi for the Brama compared directly against our own. The published specifications are sourced from VinnieRossi’s website, either directly or from the manual available for download, or a combination thereof. With the exception of frequency response, where the Audio Precision bandwidth was extended to 1MHz, assume, unless otherwise stated, 10W into 8 ohms and a measurement input bandwidth of 10Hz to 22.4kHz, and the worst-case measured result between the left and right channels.

Our primary measurements revealed the following using the line-level analog input (unless specified, assume a 1kHz sinewave at 2Vrms):

For the continuous dynamic power test, the Brama was able to sustain 483W into 4 ohms (~3% THD) using an 80Hz tone for 500ms, alternating with a signal at -10dB of the peak (31W) for 5 seconds, for 247 seconds of the 5 continuous minute before the fault protection circuit engaged due to excessive heat. This test is meant to simulate sporadic dynamic bass peaks in music and movies.

Frequency response (8-ohm loading, line-level input)

In our frequency response plots above (relative to 1kHz), measured across the speaker outputs at 10W into 8 ohms, the Brama is essentially flat within the audi band, and at -3dB right around 200kHz. The Brama appears to be AC coupled, yielding roughly -2.5dB at 5Hz. In the graph above and most of the graphs below, only a single trace may be visible. This is because the left channel (blue or purple trace) is performing identically to the right channel (red or green trace), and so they perfectly overlap, indicating that the two channels are ideally matched.

Phase response (8-ohm loading, line-level input)

Above are the phase response plots from 20Hz to 20kHz for the line level input, measured across the speaker outputs at 10W into 8 ohms. The Brama appears to invert polarity (relative to the pin2/3 –  +/- XLR standard), but only yielded +15 degrees of shift at 20Hz, and -15 degrees at 20kHz.

RMS level vs. frequency vs. load impedance (1W, left channel only)

The chart above shows RMS level (relative to 0dBrA, which is 1W into 8 ohms or 2.83Vrms) as a function of frequency, for the analog line-level input swept from 5Hz to 100kHz. The blue plot is into an 8-ohm load, the purple is into a 4-ohm load, the pink plot is an actual speaker (Focal Chora 806, measurements can be found here), and the cyan plot is no load connected. The chart below . . .

. . . is the same but zoomed in to highlight differences. Here we see that the deviations between no load and 4 ohms are small at roughly 0.08dB. With a real speaker load, deviations were smaller, at roughly 0.06dB.

THD ratio (unweighted) vs. frequency vs. output power

The chart above shows THD ratios at the speaker-level outputs into 8 ohms as a function of frequency for a sinewave stimulus at the analog line-level input. The blue and red plots are for the left and right channels at 1W output into 8 ohms, purple/green at 10W, and pink/orange at 198W (just shy of the rated output of 200W). The power was varied using the Brama’s volume control. All data are fairly closely lumped together and tell the story of the Brama’s THD performance across most all of our measurements; THD results are dominated and limited by the implementation of a tube per channel in the preamp section. Due to this implementation, varying the conditions at the speaker outputs of the Brama (which utilize transistors) does very little to change the measured THD ratios. Here, we find consistent THD ratios around 0.2% at all frequencies and power levels.

THD ratio (unweighted) vs. output power at 1kHz into 4 and 8 ohms

The chart above shows THD ratios measured at the speaker-level outputs of the Brama as a function of output power for the analog line-level input, for an 8-ohm load (blue/red for left/right) and a 4-ohm load (purple/green for left/right), with the volume set to maximum. THD ratios into 4 and 8 ohms are close (within roughly 5dB). For the 8-ohm load, THD ratios ranged from 0.005% at 50mW, up to 0.15% at the “knee” at roughly 230W, then up to the 1% THD mark at 255W. For the 4-ohm load, THD ratios ranged from 0.01% at 50mW, up to 0.15% at the “knee” at roughly 420W, then up to the 1% THD mark at 451W.

THD+N ratio (unweighted) vs. output power at 1kHz into 4 and 8 ohms

The chart above shows THD+N ratios measured at the speaker-level outputs of the Brama as a function of output power for the analog line-level input, for an 8-ohm load (blue/red for left/right) and a 4-ohm load (purple/green for left/right). THD+N ratios into 4 and 8 ohms are close (within 3-5dB). THD+N ratios range from roughly 0.05% (50 mW) to 0.15% at the “knees.”

THD ratio (unweighted) vs. frequency at 8, 4, and 2 ohms (left channel only)

The chart above shows THD ratios measured at the output of the Brama as a function of frequency into three different loads (8/4/2 ohms) for a constant input voltage that yields 50W at the output into 8 ohms (and roughly 100W into 4 ohms, and 200W into 2 ohms) for the analog line-level input. The 8-ohm load is the blue trace, the 4-ohm load the purple trace, and the 2-ohm load the pink trace. Once again, THD ratios are the same due to the tube in the preamp section, hovering at 0.15-0.2% across the sweep. The 2-ohm data stop at 500Hz due to the protection circuit, which presumably engaged due to excessive heat.

THD ratio (unweighted) vs. frequency into 8 ohms and real speakers (left channel only)

The chart above shows THD ratios measured at the output of the Brama as a function of frequency into an 8-ohm load and two different speakers for a constant output voltage of 2.83Vrms (1W into 8 ohms) for the analog line-level input. The 8-ohm load is the blue trace, the purple plot is a two-way speaker (Focal Chora 806, measurements can be found here), and the pink plot is a three-way speaker (Paradigm Founder Series 100F, measurements can be found here). Again, all THD ratios are all roughly the same, near the 0.2% mark.

IMD ratio (CCIF) vs. frequency into 8 ohms and real speakers (left channel only)

The chart above shows intermodulation distortion (IMD) ratios measured at the output of the Brama as a function of frequency into an 8-ohm load and two different speakers for a constant output voltage of 2.83Vrms (1W into 8 ohms) for the analog line-level input. Here the CCIF IMD method was used, where the primary frequency is swept from 20kHz (F1) down to 2.5kHz and the secondary frequency (F2) is always 1kHz lower than the primary, with a 1:1 ratio. The CCIF IMD analysis results are the sum of the second (F1-F2 or 1kHz) and third modulation products (F1+1kHz, F2-1kHz). The 8-ohm load is the blue trace, the purple plot is a two-way speaker (Focal Chora 806, measurements can be found here), and the pink plot is a three-way speaker (Paradigm Founder Series 100F, measurements can be found here). We find that all three IMD traces are essentially the same, again due to the limitations of tube-use in the preamp, and hover around 0.15% across the sweep.

IMD ratio (SMPTE) vs. frequency into 8 ohms and real speakers (left channel only)

The chart above shows IMD ratios measured at the output of the Brama as a function of frequency into an 8-ohm load and two different speakers for a constant output voltage of 2.83Vrms (1W into 8 ohms) for the analog line-level input. Here, the SMPTE IMD method was used, where the primary frequency (F1) is swept from 250Hz down to 40Hz and the secondary frequency (F2) is held at 7kHz with a 4:1 ratio. The SMPTE IMD analysis results consider the second (F2 ± F1) through the fifth (F2 ± 4xF1) modulation products. The 8-ohm load is the blue trace, the purple plot is a two-way speaker (Focal Chora 806, measurements can be found here), and the pink plot is a three-way speaker (Paradigm Founder Series 100F, measurements can be found here). We find identical IMD results for all three loads, at 0.4% from 40Hz to 500Hz, then down to 0.006%.

FFT spectrum – 1kHz (XLR line-level input, medium gain)

Shown above is the fast Fourier transform (FFT) for a 1kHz input sinewave stimulus, measured at the output across an 8-ohm load at 10W for the analog line-level balanced input. We see significant signal harmonic peaks up to the limits of the FFT (90kHz), ranging from the highest at 2kHz (-55dBrA, or 0.2%) down to the -130dBrA, or 0.00003%, level. Once again, the high THD results are from the use of the tube in each channel of the preamp section. On the right side of the signal peak, we find power-supply-related noise peaks at 60/180/300 Hz, but at relatively low levels. The 60Hz peak dominates at -120/–110dBrA (left/right), or 0.0001%/0.0003%. The other peaks are below -120dBrA, or 0.0001%. This FFT can be characterized as high THD, but relatively low noise.

FFT spectrum – 1kHz (XLR line-level input, low gain)

Shown above is the fast Fourier transform (FFT) for a 1kHz input sinewave stimulus, measured at the output across an 8-ohm load at 10W for the analog line-level balanced input, with the gain set to low and the volume adjusted to achieve the same output. We see essentially the same FFT as with the gain set to medium above.

FFT spectrum – 1kHz (XLR line-level input, high gain)

Shown above is the fast Fourier transform (FFT) for a 1kHz input sinewave stimulus, measured at the output across an 8-ohm load at 10W for the analog line-level balanced input, with the gain set to high and the volume adjusted to achieve the same output. We see essentially the same FFT as with the gain set to medium above.

FFT spectrum – 50Hz (line-level input)

Shown above is the FFT for a 50Hz input sinewave stimulus measured at the output across an 8-ohm load at 10W for the analog line-level input. The X axis is zoomed in from 40Hz to 1kHz, so that peaks from noise artifacts can be directly compared against peaks from the harmonics of the signal. The most predominant (non-signal) peak is the second (100Hz) signal harmonic at -55dBrA, or 0.2%, and subsequent signal harmonics can be seen down to the -120dBrA, or 0.0001%, level. Power-supply-related noise peaks are the same as the 1kHz FFT above, with the 60Hz peak dominating at -120/–110dBrA (left/right), or 0.0001%/0.0003%.

Intermodulation distortion FFT (18kHz + 19kHz summed stimulus, line-level input)

Shown above is an FFT of the intermodulation distortion (IMD) products for an 18kHz + 19kHz summed sinewave stimulus tone measured at the output across an 8-ohm load at 10W for the analog line-level input. The input RMS values are set at -6.02dBrA so that, if summed for a mean frequency of 18.5kHz, would yield 10W (0dBrA) into 8 ohms at the output. We find that the second-order modulation product (i.e., the difference signal of 1kHz) is at -60dBrA, or 0.1%, while the third-order modulation products, at 17kHz and 20kHz, are at roughly the -70dBrA, or 0.03%, level.

Intermodulation distortion FFT (line-level input, APx 32 tone)

Shown above is the FFT of the speaker-level output of the Brama with the APx 32-tone signal applied to the analog input. The combined amplitude of the 32 tones is the 0dBrA reference, and corresponds to 10W into 8 ohms. The intermodulation products—i.e., the “grass” between the test tones—are distortion products from the amplifier and are at and below the  -90dBrA, or 0.003%, level.

Squarewave response (10kHz)

Above is the 10kHz squarewave response using the analog line-level input, at roughly 10W into 8 ohms. Due to limitations inherent to the Audio Precision APx555 B Series analyzer, this graph should not be used to infer or extrapolate the Brama’s slew-rate performance. Rather, it should be seen as a qualitative representation of the Brama’s high bandwidth. An ideal squarewave can be represented as the sum of a sinewave and an infinite series of its odd-order harmonics (e.g., 10kHz + 30kHz + 50kHz + 70kHz . . .). A limited bandwidth will show only the sum of the lower-order harmonics, which may result in noticeable undershoot and/or overshoot, and softening of the edges. In this case, we find very clean corners with no over/undershoot.

Damping factor vs. frequency (20Hz to 20kHz)

The final graph above is the damping factor as a function of frequency. Both channels track very closely. We can see damping factors of roughly 200 across the entire 20Hz to 20kHz band.

Diego Estan
Electronics Measurement Specialist

Details

Parent Category: Products

Category: Amplifier Measurements

Created: 01 October 2025

Link: reviewed by Philip Beaudette on SoundStage! Hi-Fi on October 1, 2025

General information

All measurements taken using an Audio Precision APx555 B Series analyzer.

The MCA 225 Gen 2 was conditioned for 1 hour at 1/8th full rated power (~28W into 8 ohms) before any measurements were taken. All measurements were taken with both channels driven, using a 120V/20A dedicated circuit, unless otherwise stated.

The MCA 225 Gen 2 is a two-channel amplifier with a set of balanced (XLR) and unbalanced (RCA) inputs, and one set of speaker level outputs. An input of 320mVrms was required to achieve the reference 10W into 8 ohms. There were no appreciable differences observed (THD, noise, gain) between the XLR and RCA inputs, however, comparative FFTs are provided in this report. Unless otherwise stated, the XLR inputs were used for all measurements.

Our typical input bandwidth filter setting of 10Hz-22.4kHz was used for all measurements except FFTs and THD versus frequency where a bandwidth of 10Hz-90kHz was used. Frequency response measurements utilize a DC to 1 MHz input bandwidth.

Published specifications vs. our primary measurements

The table below summarizes the measurements published by Anthem for the MCA 225 Gen 2 compared directly against our own. The published specifications are sourced from Anthem’s website, either directly or from the manual available for download, or a combination thereof. Assume, unless otherwise stated, 10W into 8 ohms and a measurement input bandwidth of 10Hz to 22.4kHz:

Our primary measurements revealed the following (unless specified, assume a 1kHz sinewave at 305mVrms at the input, 10W output, 8-ohm loading, 10Hz to 22.4kHz bandwidth):

For the continuous dynamic power test, the MCA 225 Gen 2 was able to sustain about 360W into 4 ohms (~3% THD) using an 80Hz tone for 500ms, alternating with a signal at -10dB of the peak (36W) for 5 second, for 5 continuous minutes without inducing a fault or the initiation of a protective circuit. This test is meant to simulate sporadic dynamic bass peaks in music and movies. During the test, the sides and top of the MCA 225 Gen 2 were warm to the touch.

Frequency response (8-ohm loading)

In our frequency response (relative to 1kHz) plot above, measured across the speaker outputs at 10W into 8 ohms, the MCA 225 Gen 2 exhibits an essentially perfectly flat frequency response across the audioband (0/0dB at 20Hz/20kHz). The MCA 225 Gen 2 is only about 0.1dB down at 5Hz. In the higher frequencies, the -3dB point is at roughly 90kHz. In the graph above and most of the graphs below, only a single trace may be visible. This is because the left channel (blue or purple trace) is performing identically to the right channel (red or green trace), and so they perfectly overlap, indicating that the two channels are ideally matched.

Phase response (8-ohm loading)

Above is the phase response plot from 20Hz to 20kHz for the balanced line-level input, measured across the speaker outputs at 10W into 8 ohms. The MCA 225 Gen 2 does not invert polarity and exhibits at worst -20 degrees of phase shift at 20kHz.

RMS level vs. frequency vs. load impedance (1W, left channel only)

The chart above shows RMS level (relative to 0dBrA, which is 1W into 8ohms or 2.83Vrms) as a function of frequency, for the analog line-level input swept from 10Hz to 100kHz. The blue plot is into an 8-ohm load, the purple is into a 4-ohm load, the pink plot is an actual speaker (Focal Chora 806, measurements can be found here), and the cyan plot is no load connected. The chart below . . .

. . . is the same but zoomed in to highlight differences. Here we find the maximum deviation between a 4-ohm load and no-load to be around 0.04dB up to 3kHz. Beyond 3kHz, the deviations are as high as 0.32dB at 20kHz. This is an indication of a very high damping factor, or low output impedance. With a real speaker, the maximum deviations from 20Hz to 20kHz were roughly 0.06dB.

THD ratio (unweighted) vs. frequency vs. output power

The chart above shows THD ratios at the output into 8 ohms as a function of frequency for a sinewave stimulus at the analog line level input. The blue and red plots are at 1W output into 8 ohms, purple and green at 10W, and pink and orange at 200W. The 10W data yielded the lowest THD results, from just below 0.0002% from 20Hz to 500Hz, then a rise to 0.01% at 20kHz. The 1W data ranged from 0.0005% from 20Hz to 2kHz, then a rise to 0.01% at 20kHz. The 200W data ranged from 0.0006% from 30Hz to 1kHz, then up to 0.015% (left) and 0.1% (right) at 20kHz.

THD ratio (unweighted) vs. output power at 1kHz into 4 and 8 ohms 

The chart above shows THD ratios measured at the output of the MCA 225 Gen 2 as a function of output power for the analog line-level input for an 8-ohm load (blue/red) and a 4-ohm load (purple/green). The 8-ohm data ranged from 0.002% at 50mW, down to 0.0003% from 5 to 20W, then up to 0.0007% at the “knee,” at roughly 190W. The 4-ohm data ranged from 0.003% at 50mW, down to 0.0005% from 10 to 100W, then up to 0.0008% at the “knee,” at roughly 300W. The 1% THD marks were reached at 210W and 336W into 8 and 4 ohms.

THD+N ratio (unweighted) vs. output power at 1kHz into 4 and 8 ohms

The chart above shows THD+N ratios measured at the output of the MCA 225 Gen 2 as a function of output power for the analog line-level input, for an 8-ohm load (blue/red) and a 4-ohm load (purple/green). The 8-ohm data ranged from 0.02% at 50mW, down to a low of 0.0007% from 50-100W, then up to the “knee.” The 4-ohm data ranged from 0.03% at 50mW, down to a low of 0.0008% from 100-200W, then up to the “knee.”

THD ratio (unweighted) vs. frequency at 8, 4, and 2 ohms (left channel only)

The chart above shows THD ratios measured at the output of the MCA 225 Gen 2 as a function of frequency into three different loads (8/4/2 ohms) for a constant input voltage that yields roughly 50W at the output into 8 ohms (blue), 100W into 4 ohms (purple), and 200W into 2 ohms (pink). The 8-ohm data ranged from 0.0003% from 20Hz to 300Hz, then up to 0.01% at 20kHz. The 4-ohm THD data ranged from 0.0007% from 20Hz to 1kHz, then up to 0.02% at 20kHz. The 2-ohm data ranged from 0.0003% from 20Hz to 100Hz, then up to 0.03% at 20kHz. This shows that the MCA 225 Gen 2 is perfectly stable into 2-ohm loads, with low THD ratios even at 200W.

THD ratio (unweighted) vs. frequency into 8 ohms and real speakers (left channel only)

The chart above shows THD ratios measured at the output of the MCA 225 Gen 2 as a function of frequency into an 8-ohm load and two different speakers for a constant output voltage of 2.83Vrms (1W into 8 ohms) for the analog line-level input. The 8-ohm load is the blue trace, the purple plot is a two-way speaker (Focal Chora 806, measurements can be found here), and the pink plot is a three-way speaker (Paradigm Founder Series 100F, measurements can be found here). At very low frequencies, the two-way speaker yielded the highest THD ratios (0.02%), compared to 0.002% for the three-way speaker and 0.0003% of the resistive load. In the all-important 300Hz to 5kHz range, THD ratios into the real speakers were between 5dB higher and 5dB lower than the resistive load, hovering between the 0.0004-0.0007% level. At the highest frequencies, the three-way speaker yielded the highest THD ratios (0.02% at 20kHz).

IMD ratio (CCIF) vs. frequency into 8 ohms and real speakers (left channel only)

The chart above shows intermodulation distortion (IMD) ratios measured at the output of the MCA 225 Gen 2 as a function of frequency into an 8-ohm load and two different speakers for a constant output voltage of 2.83Vrms (1W into 8 ohms) for the analog line-level input. Here the CCIF IMD method was used, where the primary frequency is swept from 20kHz (F1) down to 2.5kHz, and the secondary frequency (F2) is always 1kHz lower than the primary, with a 1:1 ratio. The CCIF IMD analysis results are the sum of the second (F1-F2 or 1kHz) and third modulation products (F1+1kHz, F2-1kHz). The 8-ohm load is the blue trace, the purple plot is a two-way speaker (Focal Chora 806, measurements can be found here), and the pink plot is a three-way speaker (Paradigm Founder Series 100F, measurements can be found here). The IMD results into the resistive load range from 0.0006% up to 0.004% across the sweep. The results were similar for the two-way speaker but higher for the three-way speaker (0.002% to 0.015%).

IMD ratio (SMPTE) vs. frequency into 8 ohms and real speakers (left channel only)

The chart above shows IMD ratios measured at the output of the MCA 225 Gen 2 as a function of frequency into an 8-ohm load and two different speakers for a constant output voltage of 2.83Vrms (1W into 8 ohms) for the analog line-level input. Here, the SMPTE IMD method was used, where the primary frequency (F1) is swept from 250Hz down to 40Hz, and the secondary frequency (F2) is held at 7kHz with a 4:1 ratio. The SMPTE IMD analysis results consider the second (F2 ± F1) through the fifth (F2 ± 4xF1) modulation products. The 8-ohm load is the blue trace, the purple plot is a 2-way speaker (Focal Chora 806, measurements can be found here), and the pink plot is a 3-way speaker (Paradigm Founder Series 100F, measurements can be found here).  All three plots are essentially identical and constant at 0.005%.

FFT spectrum – 1kHz (XLR input)

Shown above is the fast Fourier transform (FFT) for a 1kHz input sinewave stimulus, measured at the output across an 8-ohm load at 10W for the balanced analog line-level input. We see that the signal’s second (2kHz) and third (3kHz) harmonics dominate at just below -110dBrA, or 0.0003%. Other signal harmonics can be seen but at -120dBrA to -130dBrA, or 0.0001% to 0.00003%. There are only four visible power-supply noise-related harmonics, but these are below the -120dBrA level, or 0.0001%. This is a clean FFT result.

FFT spectrum – 1kHz (RCA input)

Shown above is the fast Fourier transform (FFT) for a 1kHz input sinewave stimulus, measured at the output across an 8-ohm load at 10W for the unbalanced analog line-level input. The main differences between this and the balanced line-level FFT above are a lower second (2kHz) signal harmonic at -120dBrA, or 0.0001%, and a lower overall noise floor (-150dBrA vs -140dBrA), which subsequently shows a multitude of power-supply noise-related peaks around the -140dBrA level, or 0.00001%.

FFT spectrum – 50Hz (line-level input)

Shown above is the FFT for a 50Hz input sinewave stimulus measured at the output across an 8-ohm load at 10W for the balanced analog line-level input. The X axis is zoomed in from 40Hz to 1kHz, so that peaks from noise artifacts can be directly compared against peaks from the harmonics of the signal. The most dominant (non-signal) peaks are the signal’s second (100Hz) harmonic and the power-supply noise-related peak at 120Hz. Both are just below -120dBrA, or 0.0001%.

Intermodulation distortion FFT (18kHz + 19kHz summed stimulus, line-level input)

Shown above is an FFT of the intermodulation distortion (IMD) products for an 18kHz + 19kHz summed sinewave stimulus tone measured at the output across an 8-ohm load at 10W for the balanced analog line-level input. The input RMS values are set at -6.02dBrA so that, if summed for a mean frequency of 18.5kHz, would yield 10W (0dBrA) into 8 ohms at the output. We find that the second-order modulation products (i.e., the difference signal of 1kHz) are just above -120dBrA, or 0.0001%, while the third-order modulation products, at 17kHz and 20kHz, are higher at -100dBrA, or 0.001%.

Intermodulation distortion FFT (line-level input, APx 32 tone)

Shown above is the FFT of the speaker-level output of the MCA 225 Gen 2 with the APx 32-tone signal applied to the input. The combined amplitude of the 32 tones is the 0dBrA reference, and corresponds to 10W into 8 ohms. The intermodulation products—i.e., the “grass” between the test tones—are distortion products from the amplifier and are below the very low -125dBrA, or 0.00006%, level.

Square-wave response (10kHz)

Above is the 10kHz squarewave response using the balanced analog line-level input, at roughly 10W into 8 ohms. Due to limitations inherent to the Audio Precision APx555 B Series analyzer, this graph should not be used to infer or extrapolate the MCA 225 Gen 2’s slew-rate performance. Rather, it should be seen as a qualitative representation of the MCA 225 Gen 2’s mid-tier bandwidth. An ideal squarewave can be represented as the sum of a sinewave and an infinite series of its odd-order harmonics (e.g., 10kHz + 30kHz + 50kHz + 70kHz . . .). A limited bandwidth will show only the sum of the lower-order harmonics, which may result in noticeable undershoot and/or overshoot, and softening of the edges. In this case, we see a relatively clean result, with some obvious softening in the corners.

Damping factor vs. frequency (20Hz to 20kHz)

The final graph above is the damping factor as a function of frequency. We find very high damping factor values, around 500 from 20Hz to 2kHz. Above 2kHz, there is a dip in the damping factor, reaching roughly 80 at 20kHz.

Diego Estan
Electronics Measurement Specialist