Unscientific DAC Measurements

I've been comparing the new HiFiBerry DAC2 HD to the Katana Tone Board this week…only because I recently purchased both and they happened to arrive this week. It's been an interesting journey as I've been running both continuously to get them burned in (for those who believe in such things).

I felt that there was a fairly obvious difference in tone between the two…not glaring, but easily detectable, even with my 50+ year-old ears. So, I decided to connect them to my Focusrite Scarlett 2i2 audio interface and do some measurements. Now, this is not the most precise measurement device…its natural response slopes slightly down on both ends of the spectrum, but measurements are consistent from run to run, so it's adequate for comparing DACs.

I wanted to understand trends, so I measured each of the following DACs:

  • HiFiBerry DAC2 HD
  • Khadas Tone Board
  • Orchard Audio PecanPi
  • iFi Audio micro iDSD
  • iFi Audio micro iDAC2
  • iFi Audio nano iDSD
  • Allo Katana

Here are my plots:

Note that most of the DACs follow that downward bend in response above 3 kHz, with the HiFiBerry DAC2 HD being the notable exception; highs seem to be tipped up roughly 0.2 dB relative to the median of the other DACs. I would not have expected that this would be enough to for me to hear, but it's not difficult to pick it out of the bunch.

I thought I'd also have a look at step response to get a sense of what's happening in the time domain. I found another surprise with the DAC2 HD there also. Relative to all six of the other DACs, it's phase is inverted:

Here's what I'm seeing with the other six DACs:

Fortunately, it's easy enough to use Roon's Procedural EQ (under DSP settings) to invert the phase for a zone. Not sure that I can actually hear absolute phase, but for measurements, it's nice for everything to be run the same way. Note, I used the same cable for all seven DACs, so it's not a wiring issue.

I also created 2-band PEQ filter in Roon to get the frequency response of the DAC2 HD to closely match my reference DAC. Here are the settings:

Band 1:

  • Type: High Shelf
  • Frequency: 17000 Hz
  • Gain: -0.17 dB
  • Q: 0.2

Band 2:

  • Type: Peak/Dip
  • Frequency: 17500 Hz
  • Gain: -0.13 dB
  • Q: 0.6

Here's the resulting plot comparing my reference DAC to the HiFiBerry DAC2 HD:

I've saved this as a DSP preset in Roon so that I can enable it whenever I need to. Please share similar plots if you have done them. Let me know if you have questions about how I created these. Otherwise, Cheers and happy listening. 


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