Windows 7 - HDMI Audio Problem

Hi Guys,

I have an asus mobo with intel CPU onboard, which has nvidia ION as a GPU. The system is connected to a Sharp Aquos via a Marantz amplifier via HDMI.

I get Video but partial audio. I get no Windows system sound, I get only stereo sound when playing movies and music.

HDMI is set to default, speakers configured to 5.1. When I test the speakers no sound comes out, however when I'm playing music and I test the speakers I do get sound.

When I checked the properties for audio formats supported, only Dolby Prologic is shown. I don't have the option to tick DTS and WMA.

Graphic drivers, HDMI and chipset drivers where updated through Nvidia directly.

I connected the audio through SPDIF and it worked, but I prefer having sound through HDMI as I get 8 channels where as SPDIF only 2.

I've got no other ideas, anyone got any?