To use the THX logo it must be certified by Lucasfilms for a certain sound clarity, SNR, accurate sound reproduction and have a good clock generator. The amount of data going to the sound card is irrelevant: Dolby Digital EX takes has a lower bitrate than conventional analog stereo sound, which 99% of sound cards (even AC97 ones) do quite competently. Remember, Dolby Digital fits in between the sprocket holes on the projector film where the analog stereo gets long strips down the side of the film. And FYI: a standard 32 bit 33 MHz PCI slot can transmit an entire DVD18 in 2.31 minuites. THX can be done with a little as two channels of 16 bit audio, and the Audigy is decoding 6 discreet and 1 indescreet channel at 24 bits … same as a standard home theathre system. Trust me, Audio doesn’t even begin to stress an EISA bus, let alone a PCI 33 MHz 32 bit bus.