I forgot Len Feldman mentioned this in Four Channel Sound. From what I gather with the addition of rear channel phase shifting employed in the decoding process it can mostly place proper sounds in the correct corners albeit with some phase issues. Unsurprisingly according to Feldman's drawings the decoder still works best with EV-4 material.Yes it was, it did EV-4, SQ and QS automatically. Actually the EV-4 coefficients were modified to make it more like SQ (with blend). As I recall it had switchable vari-blend on the rear channels to improve front to back separation. It sounded like a great idea but In actual use it was a compromise for everything!