A/B test of two DACs – do they sound different?
Doing some measurements and changes in my audio chain, once again I had a feeling that the DAC that I have just connected into the system sounds different. Wow, better clarity and tighter, well defined bass! Not the first time such situation, right? Hopefully, my current system allows for doing A/B test without any hardware change, just switching the input selector switch on the preamp. So, I connected the newly tested DAC and my usual DAC and started to make a listening test, and also collected some measurements and files to be archived and for listening test.
Test setup
This is the schematic diagram of my DAC test setup.
PC notebook is connected, via USB-ISO isolator (this is crucial to eliminate the signal groundloop between PC, both DACs, preamp and ADC back to PC), to Topping D10s DAC. Analog signal from Topping output goes to INPUT2 of my ULTIM2 preamplifier:
Topping D10s also works as a digital bridge, sending input digital data to coaxial and optical Toslink output. I used the Toslink (again to eliminate groundloop) to send the data to my old Cambridge Audio DacMagicPlus (DM+). Analog output from DM+ is again send to the ULTIM2 preamp, INPUT1. Inputs are selectable by the input selector as seen in the ULTIM2 photo. Hopefully, the level difference at the ULTIM2 output, after switching inputs with both DACs, was less than 0.4dB.
For listening, ULTIM2 output was connected to my PMA-NC252MP power amplifier. For measuring and capturing files, ULTIM2 output was connected to E1DA Cosmos ADC stereo XLR inputs, at 4.5V input range selected.
Measurements
This is the result of THD distortion vs. output voltage, at 1kHz.
This is the result of THD+N distortion+noise vs. output voltage, at 1kHz.
We can see that the audio path with D10s has had about 4dB lower noise than the path with DM+. THD (w/o noise) is very low in both cases. Traditional multitone measurement has had dynamic range of >= 120dB in both cases. So, except for a slight noise difference, very similar.
Distortion data, DM+ and ULTIM2:
131072-point spectrum using Blackman-Harris 7 window and 4 averages
Input RMS 3.631 V
3.631 VC, 3.631 VA
3.631 V 22 - 22k UNW
Distortion at 999.9 Hz, -1.86 dBFS:
THD: -104.0 dB based on 21 harmonics [22..22000 Hz]
HHD: -130.2 dB [10 .. 22]
N: -105.1 dB [22..22000 Hz]
N+D: 31.22 uV A
THD+N: -101.5 dB [22..22000 Hz]
Distortion data, D10s + ULTIM2:
131072-point spectrum using Blackman-Harris 7 window and 4 averages
Input RMS 3.432 V
3.432 VC, 3.432 VA
3.432 V 22 - 22k UNW
Distortion at 999.9 Hz, -2.35 dBFS:
THD: -110.3 dB based on 21 harmonics [22..22000 Hz]
HHD: -132.1 dB [10 .. 22]
N: -110.1 dB [22..22000 Hz]
N+D: 14.64 uV A
THD+N: -107.2 dB [22..22000 Hz]
Listening test file
Music files were captured during testing and you may download them from
and listen to them, after unzipping. They are in 44.1kHz/24bit flac format. You may try if you hear a difference or not. In case you thing you can hear a difference, please make an ABX test and post the ABX test report (like from Foobar ABX plugin).
Deltawave results
The captured files were tested by Paul @pkane excellent Deltawave software and here are the results:
Summary
I forgot to mention that I have not heard any sound difference in a level matched A/B test (not ABX, please note), so I did not bother to make ABX test. I made the A/B test after I had a feeling I heard the difference in a sighted “test” after DAC exchange in the chain. An illusion, as usually and so many times.
Have fun with audio!![Smile :) :)](data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7)
Doing some measurements and changes in my audio chain, once again I had a feeling that the DAC that I have just connected into the system sounds different. Wow, better clarity and tighter, well defined bass! Not the first time such situation, right? Hopefully, my current system allows for doing A/B test without any hardware change, just switching the input selector switch on the preamp. So, I connected the newly tested DAC and my usual DAC and started to make a listening test, and also collected some measurements and files to be archived and for listening test.
Test setup
This is the schematic diagram of my DAC test setup.
PC notebook is connected, via USB-ISO isolator (this is crucial to eliminate the signal groundloop between PC, both DACs, preamp and ADC back to PC), to Topping D10s DAC. Analog signal from Topping output goes to INPUT2 of my ULTIM2 preamplifier:
Topping D10s also works as a digital bridge, sending input digital data to coaxial and optical Toslink output. I used the Toslink (again to eliminate groundloop) to send the data to my old Cambridge Audio DacMagicPlus (DM+). Analog output from DM+ is again send to the ULTIM2 preamp, INPUT1. Inputs are selectable by the input selector as seen in the ULTIM2 photo. Hopefully, the level difference at the ULTIM2 output, after switching inputs with both DACs, was less than 0.4dB.
For listening, ULTIM2 output was connected to my PMA-NC252MP power amplifier. For measuring and capturing files, ULTIM2 output was connected to E1DA Cosmos ADC stereo XLR inputs, at 4.5V input range selected.
Measurements
This is the result of THD distortion vs. output voltage, at 1kHz.
This is the result of THD+N distortion+noise vs. output voltage, at 1kHz.
We can see that the audio path with D10s has had about 4dB lower noise than the path with DM+. THD (w/o noise) is very low in both cases. Traditional multitone measurement has had dynamic range of >= 120dB in both cases. So, except for a slight noise difference, very similar.
Distortion data, DM+ and ULTIM2:
131072-point spectrum using Blackman-Harris 7 window and 4 averages
Input RMS 3.631 V
3.631 VC, 3.631 VA
3.631 V 22 - 22k UNW
Distortion at 999.9 Hz, -1.86 dBFS:
THD: -104.0 dB based on 21 harmonics [22..22000 Hz]
HHD: -130.2 dB [10 .. 22]
N: -105.1 dB [22..22000 Hz]
N+D: 31.22 uV A
THD+N: -101.5 dB [22..22000 Hz]
Distortion data, D10s + ULTIM2:
131072-point spectrum using Blackman-Harris 7 window and 4 averages
Input RMS 3.432 V
3.432 VC, 3.432 VA
3.432 V 22 - 22k UNW
Distortion at 999.9 Hz, -2.35 dBFS:
THD: -110.3 dB based on 21 harmonics [22..22000 Hz]
HHD: -132.1 dB [10 .. 22]
N: -110.1 dB [22..22000 Hz]
N+D: 14.64 uV A
THD+N: -107.2 dB [22..22000 Hz]
Listening test file
Music files were captured during testing and you may download them from
and listen to them, after unzipping. They are in 44.1kHz/24bit flac format. You may try if you hear a difference or not. In case you thing you can hear a difference, please make an ABX test and post the ABX test report (like from Foobar ABX plugin).
Deltawave results
The captured files were tested by Paul @pkane excellent Deltawave software and here are the results:
Summary
I forgot to mention that I have not heard any sound difference in a level matched A/B test (not ABX, please note), so I did not bother to make ABX test. I made the A/B test after I had a feeling I heard the difference in a sighted “test” after DAC exchange in the chain. An illusion, as usually and so many times.
Have fun with audio!