Problem with ALSA audio output
If you have problem with sound, disable "Headphone Jack Sense" and "Line Jack Sense" from mixer.
Also, try running an "advanced" mixer such as gnome-alsamixer, or alsamixergui. These display all the "switches", and you may find that 5.1 channel audio is misconfigured. For example, the Mic-in jack may be configured as Rear_out.