The effective of these modes varies depending on how much surround ambience has been recorded and then mixed into the front channels(again of course, no place else to put it). Many classical recordings made in a recording studio nevertheless have microphones situated so as to pick up the reflections, not just direct sound from the front. I've never heard one where there wasn't at least a small benefit; no recordings are that "dead"

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Enjoy the music, not the equipment.