Here is how to enable more than 2 speakers (channels) in Ubuntu - PulseAudio:

1.

gksu gedit /etc/pulse/daemon.conf

default-sample-channels

;

"

= 2

"

; default-sample-channels = 2

default-sample-channels = 6

2. Now you can save the changes and either restart your computer or:

killall pulseaudio && pulseaudio

3. Check to see if the channels are muted. Open a terminal and type

alsamixer



4. You can now test the channels by typing this in a terminal:

speaker-test -c 6 Again, replace the number with your number of speakers. Check to see if the channels are muted. Open a terminal and typeYou can now test the channels by typing this in a terminal:Again, replace the number with your number of speakers.

By default, PulseAudio in Ubuntu up to Jaunty is set to work with 2 speakers (front channels).Edit the PulseAudio daemon.conf file by pressing Alt + F2 and enter:And search for:. Remove "" from the begining of the line, and instead of, change it to the number of speakers your system has. For instance if you have a 5.1 system, the number should be 6, for a 7.1 system: 8 and so on.This is how that line used to look before you made any changes:And this is how it's supposed to look after: