Mark, I never limit myself to listening to 2-channel source material in stereo when I'm listening to a setup which has surround speakers. Applying processing such as DPLII extracts the surround ambience from directions other than the front which had to be mixed into the front channels because there was no place else to put it and directs it to the surround speakers where it belongs. The home listening experience is made a little more realistic.

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Enjoy the music, not the equipment.