One extra bit of good news, I was able to tell that the headphone switch is at least not broken, as I noticed in alsamixer that I can cause the Speaker volume to toggle from 100% to MM (mute) by pushing in and out the headphone.
I'm guessing there's some other missing flag somewhere, though, in order to fire up the amplifier and properly power the speakers.
One extra bit of good news, I was able to tell that the headphone switch is at least not broken, as I noticed in alsamixer that I can cause the Speaker volume to toggle from 100% to MM (mute) by pushing in and out the headphone.
I'm guessing there's some other missing flag somewhere, though, in order to fire up the amplifier and properly power the speakers.