Outputting via Coaxial SPDIF to my Marantz SR4200 - but the creative software cannot output to the centre or rear channels. Fronts are fine. Card is set to output via SPDIF and not do any decoding itself. Amplifier flags Dolby Digital instantly if I play a DVD or any other digital surround source. Why can't the soundcard give me 6 channels on its own, am I missing a setting?