5.1 channel

reference
http://www.cse.ohio-state.edu/~bondhugu/surround-pulse.shtml
http://nemonein.egloos.com/4164489

1. vi /etc/pulse/daemon.conf

uncomment default-sample-channels line
and

default-sample-channels = [the number of channels]
(6 for 5.1 ch, 8 for 7.1 ch)

2. alsamixer -c 0

control the volumes and save

alsactl store

3. restart