Whoa!
I’m quite late… I lost interest in the topic since I’ve boxed the RPi, and I think it will be hard to fit the DAC, too.
If I’ll have to un-box/re-box it in the future I will try delboy711’s solution.
Thanks!
After more than an year I restarded working on my Volumio box, annoyed by the RPi audio jack output distorsion.
For… “reasons”, I don’t have the Audiophonics DAC no more. I’ve bought a cheap replica http://www.ebay.it/itm/221987899867?_trksid=p2057872.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT, with the same DAC IC.
I’ve followed @delboy711 hint to remove pull up/down resistors (looking at this hint after some time make me feel quite dumb for not having thought about it before, since it is a quite obvious hack to do looking at the schematic diff image…), set Hifiberry DAC driver and BAM! it’s working!
Finally a clean sound!
To be honest, given my oscilloscope analysis, I’m still quite dubious about the fact that the pull up/down resistors are the problem. I’m still quite confident that there was some problem on the DAC side, despite what Audiophonics crew said.
Whatever. The new DAC is working now.
Next hard step was to let everything fit in my enclosure… https://volumio.org/forum/raspberry-barely-fit-case-t3225.html