[SofaKng]

I've been following the XBMCbuntu guide for setting up XBMC with Ubuntu (10.10 - amd64) and I'm trying to configure HDMI audio.

I've followed the guide (linked above) that has you making a bunch of changes to the ALSA configuration but I have a question.

Will this allow AC3 and DTS to pass-through over the HDMI cable? ...or is it sending only 5.1 / 7.1 PCM audio? Also, is it sending the audio untouched or is it uncompressing/recompressing it?

EDIT: Are those guides the most recent versions? I'm noticing that refer to very old posts from 2009 (re: HDMI audio having 2-3 seconds lag [hopefully this has been fixed!], etc...)

[Vicious]

Yes XBMC supports DTS and AC3 passthrough.
You say you have to make a bunch of changes to alsa, like what?
I read in the guide: "NOTE: Only if you experience difficulties with audio."
If you don't have any problems with sound, don't touch alsa.
Some changes may need to be made depending on which video card you have.