An industry insider recently admitted to me that only 30 percent of AV receiver buyers ever bother to hook up all seven channels to their receivers. That guesstimate seems a little high to me; the standard 5.1 channel setup: Left, center, right speakers upfront, and a pair of surround speakers to the sides of the main listening position can supply a truly immersive sound experience.
Seven-channel home theater adds two more speakers, placed behind the main listening position. That's tough to accomplish in rooms where the couch or chairs are up against the rear wall. There's no "rear" there, so some folks mount the rear speakers up high, or bounce the sound off the ceiling.
Still, the rear surrounds typically contribute little, so it's pretty hard to justify the added expense and hassle of running the extra wires for a marginal sonic improvement. The one exception might apply to very large rooms where the side and rear surround speakers are further apart from each other. The extra coverage may produce a more complete sense of surround envelopment.
7.1 is so rarely used the extra channels became the rationale for Dolby's new Pro Logic IIz height surround speakers that utilize receiver amplifier channels six and seven. The height channels reside in the front of the room, so it's easier to wire them. But our Pro Logic IIz listening tests were a bust, the height speakers added zilch to the surround experience.
How about you? Do you run a 7.1 channel system?
Some systems can produce 9.1 channel surround, have you tried that?
Or are you happy with 5.1?