Recently, my audio, which has been working beautifully for the past few months, stopped working. Everything checks out just fine in everything, XMMS plays, for example, but no sound is heard, and when the speakers are unplugged, they make static. This happened after logging into KDE (I normally use windowmaker, this is the first time i'd used kde since installing).

The problem seems independant of the sound system, as using esound or aRts still yields identical resutls, and yes, my speakers are plugged in.

More maddeningly, my soundcard's actual output channels are missing from the mixer, so I can't tell if they're turned off or not.

Run alsamixer from the command line, are all the bars raised up? I've had similar issues where if I hadn't run say gnome before, upon first boot it would reset my alsa levels.

Tried it.
Here's the weird thing, the bars that are simply absent in the gui-fied mixer are locked in alsamixer, with no way of turning them up.