No Stereo on ASUS M2N-SLI Deluxe

[struggler]

Hello,
I'm installing LMCE on my M2N-SLI with an Nvidia 6600 and everything looks perfect although when I play stereo sources I can't ear no sound. No problem with Dolby and DTS.

The sound chipset of this board is the Soundmax ADI AD1988B 8-Channel(S/PDIF).

Any clues?

Thanks