Somebody in here had an issue with HDMI audio.
I had the same issue where there was no audio coming from HDMI connection
using Radeon HD 2400
I was getting a message from Catalyst Center that the HDMI-DVI adapter
didn't support audio, on windows startups.
Then I found out that I had another HDMI-DVI adapter, and after trying it, I
finally got sound from the TV/speakers.
I have the HD2600 and the video card is connected to my HDTV along with other HDMI sources by connecting through a HDMI switch.
The ATI 2600 has a DVI connector ( which by definition does not carry audio), but I was pleasantly surprised that the ATI 2600 DVI connector acts as a HDMI ( video and audio). I prefer the DVI connecion because it has locking thumb screws as opposed to the HDMI which is like USB compression fit. For HD video you got to have a rock solid connection whith DVI does for good contact.
HDMI audio 
Linear Mode
