Comment 2 for bug 871633

According to the info, what you have on the front side is a line out jack, rather than internal speakers. This is why auto-mute is not enabled in the kernel.

However, that "Analog Output" has disappeared is probably something we can work around. The problem is inconsistent volume control naming in the driver, and in PulseAudio we choose the naming that works for most people, and you're one of the people where the default does not work correctly.

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. Please report back to tell us if this worked out for you. Thanks!