Comment 80 for bug 1040873

http://cgit.freedesktop.org/pulseaudio/pulseaudio/tree/src/modules/alsa/mixer/paths/analog-output-desktop-speaker.conf

[Element Speaker]
switch = off
volume = off

[Element Desktop Speaker]
required = any
switch = mute
volume = merge
override-map.1 = all
override-map.2 = all-left,all-right

what is [element desktop speaker] since none of the driver create this control ?

usually business desktops （e.g. Thinkcenter , ....）are equipped with internal speaker

and the driver can
mute speaker when line out or HP is plugged or

mute line out and speaker when HP is plugged

Simple mixer control 'Auto-Mute Mode',0
  Capabilities: enum
  Items: 'Disabled' 'Speaker Only' 'Line Out+Speaker'
  Item0: 'Disabled'