SOLUTION:
Code:
chmod -R a+rw /dev/{audio,dsp,midi,mixer,snd}
fixed two related problems on a CentOS release 4.8 machine.
xmms error:
Code:
WARNING **: alsa_get_mixer(): Attaching to mixer hw:0 failed: Permission denied"
gnome-volume-control error:
Code:
Sorry, no mixer elements and/or devices found