As of 2.6.11, I have no output out of the rear right speaker of my 4.1
surround sound setup. I am using snd-intel8x0 based on a Realtek ALC650F chip
on an nvidia motherboard.

A gentoo user with completely different hardware also ran into this:
http://bugs.gentoo.org/84276

2.6.11-mm3 fixes this problem and I've identified the specific fix, which is
already in the ALSA development tree. An ALSA developer asked me to submit the
fix for 2.6.11.x when I'd found it, so here it is :)

--
AC97 Codec
Fix stereo mutes on Surround volume control.
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Chris Wright <chrisw@osdl.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>