Thanks for your reply, desordenado. That ALSA configuration certainly helps, but there are still a lot of artifacts being added even when no audio is playing.
madplay does add it’s own high pitch whine compared to aplay playing a predecoded wav, do you think mp3123 would do a better job of decoding?
Do you really think it is a decoding issue? seems strange that there could be decoding differences.
One thing I noticed with my USB audio cards is that this one:
Is a hell of a lot noiser than this one:
I blamed it on the cheap hardware rather than on the software, in fact I can hear noises on the first one even when no decoder is running, just having it plugged to the arduino and those noises changed pitch depending on what was the processor doing, just as if noise in the electric line was getting into the audio path.
Arduino Yun 5v pin doesnt give me 5v. ( USB got less than 5v)
I have better luck to connect my USB audio adapter behind the Self Powered USB Hub.
hmmm… I guess that can also explain the USB audio card operating badly