Surround sound problem

[mikejh]

I've just connected my computer to an AV amp via S/PDIF. Playing a test file in VLC, front, centre and subwoofer are working as expected. However, the signal meant for the rear speakers is playing through the front ones. I came across a website with a 5.1 test on it, and this does play through the rear speakers (although not the subwoofer !) so I know they're connected up properly and working. I've tried both coax and optical connections - same result. This is driving me nuts. Any help greatly appreciated.

[mikejh]

Just in case anyone's losing sleep over this issue I must own up and confess that I have solved the problem by installing the latest driver for my sound card. All now working as expected.

[mikejh]

Ok, final post on this. I now have the option 'A/52 over S/PDIF' under Audio/Audio Device and this is why my amp is seeing full Dolby Digital input rather than the Linear PCM signal it was getting. I'd be willing to swear that I didn't have this option previously - it's just appeared - and I can't see why upgrading the sound card driver would cause that to happen. Any theories ?