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naudster
2018-01-18, 19:50
Hi,

Thanks for the awesome work with piCorePlayer. I've been using it for a while, but recently switched from HDMI out (to a receiver) to the Aune T1 SE MK3 USB DAC headphone amp and I'm getting a crackling/popping sound. It's only occasional when listening to CD FLAC sources, but constant with DSD files (FLAC and DSF).

I've tested a few combinations:


Pi Zero using USB - noticeable crackling
Pi Zero using HDMI out - no problem (although I can't test higher bit rates with that setup)
Pi 3 using USB - no problem!


The Pi 3 testing is using the same SD card, and therefore the exact same settings, including the in-built wifi for networking, as the pi zero.

I've played with all the options under "USB Audio tweaks" without success.

Any idea why the pi zero has a problem, but not the pi 3? Obviously the CPU is significantly less powerful, but even on the zero the CPU is 50% idle during DSD playback.

Thanks a lot.

paul-
2018-01-19, 06:59
There are some underlying kernel problems with DSD and USB, that have only been recently corrected in the 4.14.y kernel. But in general pushing sound and network across the same USB controller is the source of the problem. Moving to a USB ethernet controller might help.

naudster
2018-01-19, 20:44
Thanks paul. I'll stick with the pi3 for now and wait for the upstream kernel fixes to eventually make their way to piCorePlayer. Now to find a good use for a couple of pi zeroes in the meantime!

sbp
2018-01-19, 23:08
You could also purchase a small audio DAC hat that fits directly on the Pi zero. You can find some that deliver analogue output, some deliver digital out. There are even some that contain an amplifier so you can connect the zero directly to your speakers.

These small devices are relatively cheap and deliver great sound.