No Sound Via HDMI

[Mr. Nasty Raps]

I built an HTPC over the weekend and installed Jaunty. I'm hooked up to my TV via HDMI which normally passes sound from my other HDMI components through it's optical output to my receiver. I'm getting 1920x1080 res just fine, but there is no audio. I went to System>Preferences>Sound and set everything to "HDA ATI HDMI ATI HDMI (ALSA)", but still nothing.

I'm completely new to Linux, so please bear with me if this is something easy.

Here are the specs:
Gigabyte GA-MA78GM-US2H
AMD 7750 X2
4GB RAM
500GB HDD
LG BH08LS20 BDR
Hauppage WinTV-HVR-1600

Any info would be extremely helpful.