I have Soundblaster Z and Logitech z906 speakers. I use the 6 ch direct method, 3 aux cables to the sound card to #1 input (3aux cable in) on the Z906 speakers. I know that 6ch direct way lets the sound card do the work and if I use the optical then the speakers will do the work. However for gaming/music, etc, is there really a difference in audio quality of one over the other? I always had the impression that Optical (digital) should be better?