Comment 25 for bug 441195

I found some related bug reports in PulseAudio and ALSA
https://bugtrack.alsa-project.org/alsa-bug/view.php?id=4331
http://pulseaudio.org/ticket/457

To resume them briefly:

The STAC9200's data-sheet says that the hardware has the following layout:

front device -> softvol plugin "PCM" --> hw device ---> "Master" Volume
                                                                |-> "LFE" Volume

LFE is a mono channel (L+R) connected to the subwoofer with it's own hardware volume.

Pulse's developers assume that ALSA's master volumes should control all analog outputs (in this case "LFE + Master"). So the driver should be fixed.

ALSA developers says that the driver's job is only to expose the hardware features, (in this case two separate volumes LFE, Master), and that higher level applications should take care of that.

The reports are 14 months old...I don't think this would be fixed by either of them, maybe ubuntu should try to automatize the work around at pulseaudio install time?