Anthem MCA 225 Gen 2 Stereo Amplifier Measurements

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