Hi Mike,
Thanks for your reply. With the help of Harry I managed to fix the issue. I had to accept a drop in quality from 192khz to 96khz but I am fine with that if I can avoid bluetooth. It is a massive step up.
the issue was fixed like this:
The problem seems to be with the 2 classes of USB audio the CXA81 can handle. It is set to handle Class 2 by default, but the RPI doesnt seem to handle
To change it to class 1:
put the amp in standby mode.
hold the “speaker a/b” button until the speaker lights flash alternately.
deselect “a4” (make sure the light is off)
Hold the “speaker a/b” button again to save the changes.
This is all from the manual. (which I never read until it was pointed out to me.)
Perhaps this can help someone else as well.