Hi all,
I am using ubuntu for last three months, i have 4.1 speaker only front speakers are working rear speakers are not working.(Rear speakers are working fine in Windows) I googled and made following changes

sudo gedit /etc/pulse/daemon.conf

default-sample-channels=2 in daemon.conf

i changed it into default-sample-channels=5

But still my rear speakers are not working, could anyone help me in enabling the rear speaker.

My sound card details

00:1b.0 Audio device: Intel Corporation 82801G (ICH7 Family) High Definition Audio Controller (rev 01)
Subsystem: Intel Corporation Device d608
Flags: bus master, fast devsel, latency 0, IRQ 16
Memory at fb200000 (64-bit, non-prefetchable) [size=16K]
Capabilities: <access denied>
Kernel driver in use: HDA Intel
Kernel modules: snd-hda-intel

Front and subwoofer, LFE, are default in alsa. You can change the default using the ~/.asoundrc file.

You could have stereo out of all speakers or genuine 4.1 if that was what was being provided by the sound source as it were.

The alsa wiki is the place to look, it is not as friendly as it might be.