Ok, I have two sound cards. On is an onboard soundcard (80:01.0 Audio device: VIA Technologies, Inc. VT1708/A [Azalia HDAC] (VIA High Definition Audio Controller) (rev 10)) which is, as best I can tell from searching and several days of trying to fix this problem, incompatible with Linux. So I give up on trying to make it work.
The other soundcard is on my HD4670 Radeon (02:00.1 Audio device: ATI Technologies Inc RV710/730) which I didn't know I had until I hooked up my TV from a DVI to HDMI cable in Linux.
In GNOME, it will only play the low tones. Here's a screenshot of a movie in GNOME player with the audiometer showing:
Dragon Player works just fine.
MPlayer Media Player doesn't have sound, neither does Movie Player or Xine.
Same with MP3s, they work in some programs, not in others. They'll work in Amarok, but not in Banshee, GNOME, or half a dozen others.
I get no sound in Firefox (Youtube, etc).
Since the card is obviously compatible and working I figure there's a software issue somewhere, but I have no idea where that might be or how to fix it.
Any help would be greatly appreciated, as I am quite lost.