Problems with Multichannel Sound via HDMI

Hi,

I need help with the following please:

I have connected a HTPC (Zotac Zbox AD05, AMD RADEON 6320, Win 7 Ultimate x64) via HDMI with my AVR (Denon 3808). Unfortunately I do not recieve any kind of multichannel sound.

As long as the windows settings are on stereo I recieve DD2.0, once I change the settings to multichannel (5.1 or 7.1) I only recieve "normal" stereo (not even DD).

I have tried the following players: VLC, XBMC, WinMediaPlayer
I have tried it with video (DD5.1 and DTS) and audio (DTS and DTS-HD) files. Always the same result.

Drivers:
ATI Catalys (as of today I am not sure about the version)
Realtek High Definition Audio R 2.68 for Win 7 x64

Any ideas?
Thanks
Stefan

Thanks for the reply.

Pass through is dissabled on the AVR. Sound never comes through the TV but always through the speakers of the 5.1 System.

I only installed the Realtek drivers because they came with the Zotac. I will try to deeinstall them tonight.

I just found out that every Stereo signal (no matter if DD or not) gets treated correct by the AVR, but once the software on the HTPC recognises multichannel sound (DD, DTS) it seems that the multichannel does not reach the AVR as it does not switch to the correct format but treats it always like a stereo signal.

BR
Stefan

Do you think it still could be a pprobelm with the EDID altough Sound and Video works basically?

I tried the edid override as well as the ati drivers without the realtek ones. Unfortunately the results are the same.
Any ideas?

As I said once i change to 5.1 the signal apears to be stereo only

I see the AMD HD Device and nearly all DD / DTS Formats are Listed.

But I just found out what is the reason for the problem:

If the DENON AVR is in "detect imput signal automaticly" mode the AVR does not realise the change from "multichannel" (in windows) to DD5.1 or DTS. Once I changed this, everything works fine.

However thanks a lot for your help.

BR
Stefan