Jordan, I assume that you're speaking of the surrounds in a 5.1 rather than 7.1 setup. If so, keep in mind that the QS8s will still be "side surrounds" even though they're mounted on the back wall. As such they should be about 6' high and widely separated, say to about 1' from the side walls(or where the side walls would be).

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Enjoy the music, not the equipment.