Extra "knobs" for those who still struggle with USB DAC

Hi, I am a Newbi on Volumio. Currently RPi3 and my OPPO-105 are giving me pops and clicks during playback. After some study on the internet, I start to realize why. Given the hardware limit of Raspberry Pi 3, i.e., USB output and ethernet sharing the same USB bottleneck, I am wondering if there is anything in the software side to mitigate the problem.

A few things come to mind:

  • Give USB output the highest priority so the ethernet activities will not degrade the USB output. Of course, one needs to increase the buffer size.
  • To push the idea to the extreme, one can implement 100% buffer in Volumio and then turn off the WIFI interrupt till the playback is done.
  • Capture and analyze the USB digital output data and give insight on when pops and clicks occur what exactly happen. And then back paddle to figure out how to eliminate the problem.
  • How does Volumio handle data error event? Is there any resend in case of data corruption? Is there any debug mode that one can see the resend log?

Am I too crazy?

Also, some USB DACS seem to do just fine, according to the input in the forum but my OPPO-105 does not, This makes me wonder if there are many intrinsic differences in the designs of USB DACs, such as buffering on the playback side…

It mainly depends on your system configuration and what you play:

  • Hi Res files are most likely to create clicks
  • Don’t play while your library is scanning
  • Use ethernet when possible

There is not a definitive answer to this problem: for example I hear small clicks only with one of my 5 USB DACs. Reason is the USB receiver which somehow handles data a bit differently than the others.
What kind of files you play? Based on that the only real solution would be changing platform…

I played Apple lossless M4A files ripped from my own CD collection, WIFI streamed from my NAS, a WDMyCouldMirror. And I play as it is, without any re-sampling. The condition should not be a challenging one. And it still clicks on my OPPO-105. When I play the files from a USB stick inserted to RPi, it runs perfectly.
That’s why I am wishing there is a knob in Volumio that can prevent the WIFI interrupting the USB data transmitting.