USBAudio distorted sound


New member
I am working on a synth project on the Teensy4.1.
I am using the audio board, and (in particular during development) audio output via USB. The latter started to produce strong audio artefacts, while analog out is clean.
It sounds a bit as if the cpu can't keep up calculating the audio buffer in time, but the audio library reports below 0.6 cpu usage, and the analog output is fine, so it can't be that.
I saw an older thread about crackling noise in the USBAudio due to sampling rate issues iirc. What is the latest state on that? Any other known performance issues with USBAudio? It seems to get better if I add some 'sleep(10)' in the main loop (which reads the pots and receives midi). The artefacts come in bursts, sometimes it is fine for a minute, and then it starts again, to the point that the original sounds can hardly be recognised. Any hints what could be the issue?