Got the Khadas board in a week ago or so. Looked around the house for a case, found an old Water Testing Kit that came in a clear plastic box. Couple of notches and some 3M mounting squares later.. the board is no longer naked!
No probs using spdif from allo digione. I powered the board with an allo 5V ps which worked great. Then I plugged board into a free pi3b usb port and setup MPD to output to both digione and usb. Idea was some A/B testing against my tda1543x4 dac. Anyways, 16 bit unprocessed via usb was fine. Higher bits (32) I was getting pops and crackles. Also the pi3b usb dumps processing noise unlike the 5v ps.
Few days later I setup the board on a win7 box with Thesycon drivers. I saw the board is using the same idents as the xmos dj kit. This means finding v4 licensed drivers are out. Latest I found was v3.34 (2016). The win7 box usb was much cleaner than the pi, similar to direct 5v. However the popping issues remained when playing 16 bit with DSP processing on fb2k (Sonarworks). fb2k does internal 32bit. Setting output to 24bit improves the clicking.. I installed a dsp called smart dither and got decent results limiting the stream to 21 bits. I will have to experiment some more to determine the max rate. As you window the rate down. the clicking/popping volume drops.
Suffice to say I’m running into issues with usb, both via linux in pi, and windows with drivers. I tried a different usb-c cable with similar results. DSD via usb is perfect (DoP, DSD64 and DSD128). Unprocessed 16bits perfect. Higher, issues appear. Same results too with the v2.24 (2014) Khadas linked drivers btw.
As for sound - biggest takeaway I found is how “right” my tda1543 is. No big differences in tonality against Khadas. Though I felt I “enjoyed” the tda more.
mcgo