On my laptop, Alsa Mixer and the Pulse Audio volume control applet show two channels which both control different subsets of the laptop's built-in speakers; Master and "Master Mono". I think Master controls the smaller speakers and "Master Mono" the larger/bass speakers. By default, the Pulse volume control applet (and also the dedicated volume keys on my laptop) only control Master, and ignore "Master Mono". This leaves "Master Mono" set at a high volume all the time, which sounds crap. To WAR this issue, in Gnome, I go to System -> Preferences -> Hardware -> Sound, and change the selection in the list box under "Default Mixer Tracks" to include both Master and "Master Mono". Now the volume applet and volume keys control both channels, which works great. This should be automatic; I shouldn't have to configure this myself. Attaching output from "amixer -c0".
Created attachment 340645 [details] amixer -c0 output
Hmm, your laptop has bass speakers? Uh, what kind of zombie laptop is that? Sounds like a reasonable thing to do.
Hmm, I am not sure we really should bond this. We have no clue what might be connected to the Master/Master Mono outputs of norma HDA cards. In your case Master seems to have connected proper speakers, and master Mono bass speakers. But we cannot know that.
PA In rawhide should now handle this properly.