What to do if sound goes to dummy output
Solution 1:
Not sure if you are still facing this problem. If you do try this. It worked for me:
pulseaudio -k
Source:http://www.reddit.com/r/linux/comments/1mb5ns/please_help_me_restart_sound_system_in_linux_mint/
Solution 2:
My solution was to:
cd /dev/snd; sudo chmod a+rw *; pulseaudio -k
I noticed that the neither gnome sound setup or alsamixer was picking up the device as a normal user, but alsamixer was picking up the device as root. All good now.