Vista and 7.1 surround sound

Hi everyone,

I run Vista Ultimate on an Asus A8N-Sli Premium motherboard, which is
equipped with a Realtek AC97 audio adapter (fully 7.1 enabled sound).

Since I've upgraded to Vista I've been able to persuade vista to let me run
standard output out of Itunes through both front and rear speakers. I have
found the Speaker Fill Enhancement through "Sound" in Control Panel, but that
forces a reverb and vocal cancelling effect on the rear speaker output
(mimicking some form of surround sound I guess) .

Is there anyway to persuade Vista to output an unedited version of the audio
output through the rear speakers? The Realtek drivers are enabled to output
through all speakers, but it seems Vista won't send the audio through the
rear speakers unless the speaker fill enhancement is enabled.

Any ideas?

Cheers

Morose