EMM Labs DV2i Streaming DAC-Preamplifier Measurements

Link: reviewed by Phil Gold on SoundStage! Ultra on April 1, 2025

General Information

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

The EMM Labs DV2i was evaluated as a DAC and conditioned for 30 minutes at 0dBFS (volume set to maximum) into 200k ohms before any measurements were taken.

The DV2i is marketed as an integrated DAC because it includes a digital volume control and streamer section. The volume-control knob is on the front panel. The DV2i offers six digital inputs: coaxial S/PDIF (RCA), optical S/PDIF (TosLink), AES-EBU (XLR), USB, a proprietary EMM Labs input, and a network (ethernet) digital input. There are two line-level outputs: balanced (XLR) and unbalanced (RCA). Comparisons were made between unbalanced and balanced line level outputs, where no appreciable differences were seen other than the extra 6dB of signal over the balanced outputs. 1kHz FFTs are nonetheless provided for both balanced and unbalanced outputs.

There are two technologies to make note of: the D2Vi’s proprietary “adaptive” filter, intended to give ideal time-domain or frequency-domain response depending on the characteristics of the incoming signal; and the single-bit (AKA DSD) digital-to-analog converter technology, once again proprietary to EMM Labs. These provide unique performance characteristics.

The analyzer’s input bandwidth filter was set to 10Hz-22.4kHz for all measurements, except for frequency response (DC to 1 MHz), FFTs (10Hz to 90kHz), and THD vs. frequency (10Hz to 90kHz). The latter was to capture the second and third harmonic of the 20kHz output signal.

The DV2i’s digital volume control offers 100 volume steps (the user can also select “dB” instead of “1” to “100” on the display). Volume steps 0 through 12 offer 2dB increments, levels 13 through 40 yield 1dB, and 41 through 100 yield 0.5dB resolution.  Channel-to-channel deviation was very good, at around 0.006-0.008dB throughout the range.

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

Published specifications vs. our primary measurements

The table below summarizes the measurements published by EMM Labs for the DV2i compared directly against our own. The published specifications are sourced from EMM Labs’s website, either directly or from the manual available for download, or a combination thereof. Assume, unless otherwise stated, 1kHz at 0dBFS into 200k ohms and a measurement input bandwidth of 10Hz to 22.4kHz:

Our primary measurements revealed the following using the coaxial input and the balanced line-level outputs (unless specified, assume a 1kHz sinewave at 0dBFS, 200k ohms loading, 10Hz to 22.4kHz bandwidth):

Frequency response vs. sample rate (16/44.1, 24/96, 24/192)

The plot above shows the DV2i’s frequency response as a function of sample rate. The blue/red traces are for a 16-bit/44.1kHz dithered digital input signal from 5Hz to 22kHz, the purple/green traces are for a 24/96 dithered digital input signal from 5Hz to 48kHz, and finally orange/pink represents 24/192 from 5Hz to 96kHz. The behavior at low frequencies is the same for all sample rates—perfectly flat down to 5Hz. The behavior at high frequencies for all three digital sample rates is soft filtering at 24/96 and 24/192, and closer to brickwall-type filtering at 16/44.1. For all three sample rates, the responses are at -0.25dB at 20kHz. The -3dB points for each sample rate are roughly 21kHz, 41kHz, and 70kHz, respectively.

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

The graph above shows the results of a linearity test for the coaxial digital input (the optical input performed identically) for both 16/44.1 (blue/red) and 24/96 (purple/green) input data, measured at the balanced line-level output of the DV2i. For this test, the digital input was swept with a dithered 1kHz input signal from -120dBFS to 0dBFS, and the output was analyzed by the APx555. The ideal response is a straight flat line at 0dB (i.e., the amplitude of the digital input perfectly matches the amplitude of the measured analog output). The 24/96 input data is essentially perfect down to -120dBFS, while the 16/44.1 input data performed well, only over-responding by 3dB (left/right) at -120dBFS. The 24/96 data yielded such superb results that we extended the sweep down to . . .

. . . -140dBFS. Above we see that even at -140dBFS, the DV2i is only overshooting by 2-5 dB between -140 and -130dBFS. This is an exemplary linearity-test result.

Impulse response

The graph above shows the impulse responses 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, fed to the coaxial digital input, measured at the balanced outputs, into a 200k ohm load for the left channel only. We can see that DV2i yields an impulse response with essentially no pre- or post-ringing behaviour, or one that emulates a non-oversampling DAC. This is a surprising result given the extended and near brickwall-type frequency response for a 16/44.1 input signal. The DV2i’s adaptive filters appear to, at least according to our tests, provide the best of both worlds: near perfect time-domain and frequency-domain response.

J-Test (coaxial input)

The plot above shows the results of the J-Test test for the coaxial digital input measured at the balanced line level output of the DV2i. 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 (fundamental at 250Hz) down to -170dBrA for the odd harmonics.  The test file can also be used in conjunction with artificially injected sinewave jitter by the Audio Precision, to also show how well the DAC rejects jitter.

The coaxial input shows a strong J-Test result, with peaks visible, but only below the -140dBrA level centered around the main signal peak.

J-Test (optical input)

The optical input shows effectively the same result as the coaxial input.

J-Test (AES-EBU input)

The AES-EBU balanced input shows basically the same result as the coaxial and optical inputs.

J-Test (coaxial input, 2kHz sinewave jitter at 100ns)

The plot above shows the results of the J-Test test for the coaxial digital input (the optical and AES-EBU inputs behaved the same) measured at the balanced line-level output, with an additional 100ns of 2kHz sinewave jitter injected by the APx555, which would manifest as sideband peaks at 10kHz and 14kHz, without perfect jitter immunity. The results show no visible sidebands. This is further evidence of the DV2i’s strong jitter immunity.

Wideband FFT spectrum of white noise and 19.1kHz sinewave tone

The plot above shows a fast Fourier transform (FFT) of the DV2i’s balanced-line level output with white noise at -4 dBFS (blue/red) and a 19.1 kHz sinewave at 0dBFS fed to the coaxial digital input, sampled at 16/44.1 (purple/green). There is a soft roll-off above 20kHz in the white-noise spectrum. This contradicts the brickwall-type results we found in our frequency response plots at 16/44.1. The DV2i, with its adaptive filters, appears to behave differently depending on the type of signal fed to it (we assume that’s the point). Most importantly, there are absolutely no imaged aliasing artifacts in the audioband above the -135dBrA noise floor. The primary aliasing signal at 25kHz is heavily suppressed at -120dBrA. The general rise in the noise floor above 20kHz is likely due to the DV2i’s DSD processing.

THD ratio (unweighted) vs. frequency vs. load (24/96)

The chart above shows THD ratios at the balanced line-level output into 200k ohms (blue/red) and 600 ohms (purple/green) as a function of frequency for a 24/96 dithered 1kHz signal at the coaxial input. The 200k and 600 ohms data are identical throughout the audioband, which is an indication that the DV2i’s outputs are robust and can handle loads below 1k ohms with no difficulty. There was an evident difference in THD ratios between the left and right channels, with the left channel outperforming the right by about 5dB from 20Hz to 2kHz. THD ratios (left channel) ranged from 0.00009% from 20Hz to 1.5kHz, then up to roughly 0.001% at 4.5kHz through to 20kHz. The higher THD ratios at higher frequencies were seen in all plots and are due to the rising high-frequency noise floor due to the DSD processing (the analyzer cannot assign a THD value below the noise floor).

THD ratio (unweighted) vs. frequency vs. sample rate (16/44.1, 24/96)

The chart above shows THD ratios at the balanced line-level output into 200k ohms as a function of frequency for a 16/44.1 (blue/red) and a 24/96 (purple/green) dithered 1kHz signal at the coaxial input. The 24/96 data (left channel) consistently outperformed the 16/44.1 data by 10dB from 20Hz to about 2kHz due to the inherently higher noise floor at 16 bits (i.e., the analyzer cannot assign a THD value below the noise floor). THD ratios with 16/44.1 data ranged from 0.0003% from 20Hz to 2.5kHz, then up to roughly 0.001% at 4.5kHz through to 20kHz. The higher THD ratios at higher frequencies were seen in all plots and are due to the rising high-frequency noise floor because of the DSD-type processing.

THD ratio (unweighted) vs. output (16/44.1, 24/96)

The chart above shows THD ratios measured at the balanced outputs as a function of output voltage for the coaxial input into 200k ohms from -90dBFS to 0dBFS at 16/44.1 (blue/red) and 24/96 (purple/green), with the volume set to maximum. Once again, the 24/96 outperformed the 16/44.1 data, with a THD range from 1% at 300uVrms to 0.0002% at 4Vrms, while the 16/44.1 ranged from 3% down to 0.0003% at the maximum output voltage of 4Vrms.

THD+N ratio (unweighted) vs. output (16/44.1, 24/96)

The chart above shows THD+N ratios measured at the balanced outputs as a function of output voltage for the coaxial input into 200k ohms from -90dBFS to 0dBFS at 16/44.1 (blue/red) and 24/96 (purple/green), with the volume set to maximum. The 24/96 outperformed the 16/44.1 data, with a THD+N range from 5% down to 0.0005% at 4Vrms, while the 16/44.1 ranged from 30% down to 0.002% at the maximum output voltage of 4Vrms.

Intermodulation distortion vs. generator level (SMPTE, 60Hz:4kHz, 4:1; 16/44.1, 24/96)

The chart above shows intermodulation distortion (IMD) ratios measured at balanced output for 16/44.1 (blue/red) input data and 24/96 input data (purple/green), from -60dBFS to 0dBFS. Here, the SMPTE IMD method was used, where the primary frequency (F1 = 60Hz) and the secondary frequency (F2 = 7kHz) are mixed at a ratio of 4:1. The SMPTE IMD analysis results consider the second (F2 ± F1) through the fifth (F2 ± 4xF1) modulation products. The 16/44.1 data yielded IMD ratios from 2% down to 0.002% at 0dBFS. The 24/96 data yielded IMD ratios from 0.3% down to 0.0006% from -5 to 0dBFS.

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 balanced output into 200k ohm for the coaxial digital input, sampled at 16/44.1. We see signal harmonics at 2 and 3kHz. The second (2kHz) harmonic is at -125/-130dBrA, or 0.00006/0.00003%, and the third harmonic (3kHz) is at -130dBrA (right visible only), or 0.00003%. There are also no power-supply noise peaks to speak of to the left of the main signal peak.

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 balanced output into 200k ohms for the coaxial digital input, sampled at 24/96. Due to the increased bit-depth, the noise floor is much lower compared to the 16/44.1 FFT at a low -150dBrA. We see signal harmonics ranging from -120dBrA to -140dBrA, or 0.0001% to 0.00001%, at 2/3/4/5kHz. Here also, there are no power-supply noise peaks to speak of to the left of the main signal peak. The rise in the noise floor above 20kHz is due to the DSD processing.

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

Shown above is the fast Fourier transform (FFT) for a 1kHz input sinewave stimulus, measured at the unbalanced output into 100k ohm for the coaxial digital input, sampled at 24/96. It is essentially identical to the FFT above using the balanced inputs.

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

Shown above is the fast Fourier transform (FFT) for a 1kHz input sinewave stimulus, measured at the balanced output into 200k ohm for the coaxial digital input, sampled at 16/44.1 at -90dBFS. We see the signal peak at the correct amplitude, and no signal harmonics or noise peaks.

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

Shown above is the fast Fourier transform (FFT) for a 1kHz input sinewave stimulus, measured at the balanced output into 200k ohm for the coaxial digital input, sampled at 24/961 at -90dBFS. We see the signal peak at the correct amplitude, and essentially no signal harmonics or noise peaks.

FFT spectrum – 1kHz (digital input, 24/96 data at -80dBFS)

This is not a test we typically do, but because the DV2i has an onboard volume control, we wanted to show if there were differences between lowering the signal level of the analyzer versus using the volume control at its lowest level (-80dBFS). Shown above is the fast Fourier transform (FFT) for a 1kHz input sinewave stimulus, measured at the balanced output into 200k ohm for the coaxial digital input, sampled at 24/961 at -80dBFS with the volume set to maximum but with the analyzer’s signal level reduced to output the correct level. We see the signal peak at the correct amplitude, and essentially no signal harmonics or noise peaks.

FFT spectrum – 1kHz (digital input, 24/96 data at 0dBFS with volume control set to -80dBFS, its lowest level)

This is not a test we typically do, but because the DV2i has an onboard volume control, we wanted to show if there were differences between lowering the signal level of the analyzer versus using the volume control. Shown above is the fast Fourier transform (FFT) for a 1kHz input sinewave stimulus, measured at the balanced output into 200k ohm for the coaxial digital input, sampled at 24/961 at 0dBFS with the volume set to minimum (-80dB). We see essentially the same FFT as above with the volume at maximum and the input signal at -80dBFS. This is good evidence for EmmLabs’s claims of a transparent digital volume control.

Intermodulation distortion FFT (18kHz + 19kHz summed stimulus, 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 balanced output into 200k ohms for the coaxial input at 16/44.1. The input dBFS values are set at -6.02dBFS so that, if summed for a mean frequency of 18.5kHz, would yield 4Vrms (0dBrA) at the output. We find that the second-order modulation product (i.e., the difference signal of 1kHz), is not visible above the noise floor at -135dBrA, or 0.00002%, and the third-order modulation products, at 17kHz and 20kHz, are at -135dBrA, or 0.00002%. The signals to the right of the 18kHz + 19kHz summed sinewave are presumably the result of aliasing artifacts due to the nature of the adaptive digital filter.

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

Shown above is an FFT of the intermodulation distortion (IMD) products for an 18kHz + 19kHz summed sinewave stimulus tone measured at the balanced output into 200k ohms for the coaxial input at 24/96. The input dBFS values are set at -6.02dBFS so that, if summed for a mean frequency of 18.5kHz, would yield 4Vrms (0dBrA) at the output. We find that the second-order modulation product (i.e., the difference signal of 1kHz) is at -135/-125dBrA (left/right), or 0.00002/0.00006%, and the third-order modulation products, at 17kHz and 20kHz, are at -130dBrA, or 0.00003%.

Diego Estan
Electronics Measurement Specialist