On the PS3 side, there are a couple of settings that have to be changed in the PS3 to get HDMI and multi-channel formats working. It's easy to just change one setting and then wonder why it still doesn't work.

Check out this guide. I didn't read it but I think it applies. There are some youtubes on it as well if you search.

PS3 Audio output for HDMI

With great power comes Awesome irresponsibility.