I seek simply to have a dolby prologic decoder classic on my HTPC. It must be capable of decoding from external sources of digital inputs which is SPDIF Toslink and analog which is especially digital. I had a LaserDisc player connected by fiber optics, or by conventional analog sound input. I have a TV Tuner and a cable box connected. I had a sound card TerraTec Aureon 5.1 but I does not know how to decode the same in Dolby Surround.