Syed, since you're sitting very close to the wall behind you, there's very little difference between having the QS8s mounted on the side walls slightly farther back than directly to the side, and mounting them on the back wall spread very widely(almost to the side walls or where the side wall would be). Place them about 2-3' above ear level and at least a few feet to the outside of the listening position on each side.

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Enjoy the music, not the equipment.