Other people have asked this before, but most such
threads seem to
always come to "just use Jack." Is it impossible to directly access
these devices from Alsa? I'm not wanting anything fancy here. If I do
have to write a .asoundrc, where do I get the information that HDSPMixer
seems to innately know about how my channels map to the hardware so I
can create one?
I solve this problem using an ALSA+PulseAudio+Jackd+ALSA sandwich, so
that ALSA-only apps talk to ALSA which delivers to Pulse (which hands
directly to Jack), non-Jack apps which do Pulse talk to Pulse (still
handing to Jack), and everything else talks directly to Jack. Here's a
summary:
http://linuxlive.joshuacorps.org/?p=57
J.E.B.