I don't honestly know.

However, I remember (and hopefully I'm not mis-remembering here) reading/hearing an interview with a pulseaudio developer who said something about pulseaudio using features in sound card drivers that aren't normally used and consequently weren't tested properly and therefore exposing bugs in the drivers, so my money is on it being a problem with the snd_usb_audio driver and musb is just showing up in the trace just because the driver uses it. I'm guessing here but I suspect backporting a newer version of the snd_usb_audio driver will fix this, but I could be on the wrong track.

Maybe some debug info from pulseaudio would be useful here, anyone know how to get it?