Yes whip, the position Alan describes, and about 3 feet above ear level is the most commonly suggested position for the surrounds. This isn't to say that the back wall can't be used reasonably well, especially with multi-polar speakers such as the QSs which have very broad dispersion.

Back on the receivers, it may be to your benefit to consider some of the fine 6.1 receivers available in the $400-$500 area. The Denon 1803 is very good and the Onkyo 600 and Yamaha 5560 are also worth considering.

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Enjoy the music, not the equipment.