Bob, along with Bruno, I have to comment that your view about "strait 2 channel stereo" isn't very realistic. My own listening is almost entirely classical(including Bach, which I'm listening to at the moment on the KUSC stream)and I'd never consider limiting myself to listening to 2-channel source materials on only front speakers when surrounds are available. Most of the sound at a concert comes to us as reflected ambience from directions other than the front. This is picked up by the mikes and has to be mixed into the front channels in 2-channel source material(there's no place else to put it). A mode such as DPLII detects the phase differences in this mixed-in surround material, extracts it from the front channels and directs it to the surrounds where it belongs. This makes the overall listening experience a little closer to reality and more enjoyable. The difference can be immediately appreciated by suddenly switching on the remote from surround to stereo and hearing the sound field collapse toward the front.
