Comment 25 for bug 449783

Also experiencing similar things with Ubuntu Karmic 64bit.

Whenever I reboot, all audio channels reduce down to 14% volume apart from the Center channel (which stays at 100%).
A quick trip to pavucontrol lets me adjust the volumes back to 100% and everything works fine.

On a sidenote, why does the gnome volume applet not allow you to adjust the channels separately, it took me ages to work out that I had to use pavucontrol.