Quad, Dolby Pro-Logic, Dolby Digital yet I always seem to come back to 2ch. I find with decent components and speakers with good presence and soundstage, TV and movies are to me still quite enjoyable in 2.0. Besides I'm more likely to have music on. Gee for some of us it probably doesn't seem that long ago buying that Y cable to hook the VCR into the stereo (stereo VCR's were expensive when introduced). I was the odd one out though, had a laser disc player. No worries about the rewind thing on rentals.