Mikael,
Make sure you have the latest Auzentech drives installed
http://www.auzensupport.com/site/download/updates.php
and ensure you have the latest DVD9 patch (2029) installed.
In the Auzen console launcher (Entertainment mode) go to the HDMI tab (far right side of the menu) and select 'Use Hardware default and under the X-Fi settings check the 'Play audio from speakers through HDMI' tab.
Chech your sound properties in the system tray. Open playpack device (right click) and select Auzen 'Speakers' - check properties and ensure 7.1 is checked.
Launch DVD9 (Ultra) and you should see HDMI in the audio drop down list and the audio output should be set to 'non decoded High Def Dolby/DTS pass through to external device)
this should work.
I don't know what A/V amp you are using but some amps like the Denon 2809 (pre 2007) won't hand shake with PC's due to the EDID code.
I hope this helps..
Gerry