Surround sound

I just got a set of Logitech Z-5500 speakers and connected them to my Asus P5E's onboard SoundMAX HD audio via the coaxial S/PDIF. I'm running the latest drivers from the Asus website.

THE PROBLEM: the output is entirely 2.1 channel in WinXP64, when it should be 5.1. I cannot coax even a whisper from the rear speakers, or from the center, or from direct-to-woofer output.

The surround speakers test just fine in the speaker-controller's own built-in test mode, and in Vista, but not in XP. In the SoundMAX control panel, I have set my configuration to Dolby Digital 5.1, but when I perform the channel test, the only sound comes from the front L&R speakers and from the subwoofer.

The LCD screen on the speakers' control center displays the text "No Digital Data" whenever no sound is being output to it, and this is precisely what it does when it ought to be playing through the rear speakers.

I'm almost certain it's some bit of configuration I've neglected to do, somewhere deep in the bowels of SoundMAX or in Windows. I need to get 5.1 working.

Please help, for to assist the needy is divinity. And divinity is sexy.

 

PROGRESS!

For a moment I thought I had fixed, but alas, 'twas not so.

I did find that VLC will not properly play multichannel audio on my computer. I played a DVD with Zoom player and the rear channels worked just fine.

Problems still persist: When I set my speaker configuration to 5.1 in the SoundMAX control panel and cycle the test noise to each speaker, the center and rear left and right channel remain silent. I have a similar problem in games (e.g. in Oblivion, when something is behind me I cannot hear it at all).

SOMEONE has a big enough brain to help me. Please, any ideas at all are welcome!