As of 2/27/97, linux-pmac has pretty good sound output support.  The 
latest linux-pmac kernel has full audio output support.  Sound input...
will work eventually (give us some time... we'll get around to it... ;-)
 
Sound playthrough (for CD / line-in / mic) works fully.  Use the 
sndvolmix program to control it.  Even better than MacOS -- you can use
any and/or ALL of those devices (AND /dev/audio or /dev/dsp) 
simulataneously (hey, it's a mixer; that's what it's _supposed_ to 
do...).
 
sndvolmix can be found in the pmac-utils package (currently at
ftp.fys.ruu.nl:/uploads/hees).
 
28-Feb-97: sound driver info added by slipcon@cs.jhu.edu
jonh@cs.dartmouth.edu
22-Mar-97: updated by Bibek Sahu [scorpio@dodds.net]
14-May-97: pointer to sndvolmix. Brad.Sawatzky@usask.ca

You can use 'cat __.au > /dev/audio' to play .au files, it works spiffy.
playing audio cd's can be controlled with the cdtool package.
17-Jun-97 wj@acpub.duke.edu