Comment 7 for bug 871633

Pavel did you try the fix suggested above?

"Open
/usr/share/pulseaudio/alsa-mixer/paths/analog-output-speaker.conf

Change:

[Element Front]
switch = mute
volume = merge
override-map.1 = all-front
override-map.2 = front-left,front-right

To:

[Element Front]
switch = ignore
volume = ignore

...and reboot to try the new settings."