HiFiBerry DAC

Posted by trig on September 1, 2014

We recently published a project guide for the installation of a HiFiBerry DAC on a Raspberry Pi set up as a Squeeze Player using PiCorePlayer. First impressions were good, but we didn't include any comparison testing because we were busy with other things. 

Last week we made some time to perform a blind test. Three listeners, one male, two female, listened to a number of different tracks. During playback of each track, the sources were switched periodically between "Source A" and "Source B". The listeners, of course, did not know the identity of the sources. The listeners were allowed to listen to different tracks until each had come to a conclusion, and then they shared their opinions. The digital sources (all squeezebox players) were set to maximum output to avoid any distortion from digital volume control. In each of the setups we were prepard to adjust the volume in the pre-amp stage, but in fact the volumes were so close no adjustment was required. The tracks were all FLAC files, CD-quality (16/44) or better (24/48 and 24/96).

A fourth member of the party selected the tracks and switched the sources which had been synchronized to simultaneously play the same material from the Squeeze server. Clearly this was only a single-blind test as the source switcher knew the identity of the sources. However he was under instructions to get out of the way and not pass comment. It was decided that it would be unnecessary for him to wear a paper bag over his head as long as he behaved in accordance with the rules and expressed no opinions. 

The Raspberry Pi + HiFiBerry DAC combo was tested in two configurations:

  1. Compared to a Logitech Touch delivering coaxial SPDIF to a Benchmark DAC1. The playback chain for both sources was via a Rogers tube integrated Pre/Power amp and Sonus Faber Liuto speakers.
  2. Compared to a Squeezebox Player using PiCorePlayer delivering audio over HDMI to a Classe SSP. The playback chain was Classe SSP/PreAmp to Classe Power amp and Sonus Faber Cremona M speakers.
The results surprised all the participants. On some tracks, the listeners could detect no differences. On others, one source was preferred but only slightly. In both comparison sets, it turned out that the HiFiBerry Pi was the source that was just slightly less preferred. Our expectation, insofar as some of us had expectations, had been that the sources that used the expensive DAC components would outshine the HiFiBerry DAC on all material, but the results confounded that expectation. The differences in playback quality in both our setups were minimal. Where the listeners felt there was a difference was in the breadth and depth of the soundstage and in some difficult-to-define "smoothness". 
We all considered this a great result for the 27 euro HiFiBerry DAC. 

We then moved the HiFiBerry DAC to its originally intended location, directly driving a venerable B&K power amp and a pair of decent two-way outdoor speakers of unknown origin, pointed towards the swimming pool and deck. Everything sounded just fine, and only improved as we continued to appraise the setup over a couple of bottles of white wine. For this kind of application the HiFiBerry DAC is much better than adequate, and for not much more than a good bottle of New Zealand Sauvignon Blanc. And now we know it's well-enough behaved to allow indoors too.

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