I want to acheive the following:
A USB DAC is connected to a linux box. So far no issue...
card 1: Device [USB Audio Device], device 0: USB Audio [USB Audio] Subdevices: 1/1 Subdevice #0: subdevice #0
now my target is to have multiple apps playing back using alsa's dmix module, and those virtual channels should be independent controllable using alsamixer (is this even possible??) - is it possible to map dmix channels to applications? so I could for example have mpd playing always to 2.1 and another app to 2.2?