Quote Originally Posted by Serpicode
I have a fairly big room, 18' deep by 24' wide. But my couch is against the wall (and my wife won't let me move it). I have an easy 7' feet on either side of my couch before you hit the wall. Thanks for all the advice guys. I'm just a little disappointed......what's the point of having 6.1 if your not gonna use it, ya know!
Got bad news for you ... with the couch against the wall, you're better off without the rear center speaker. Ideally, in a 6.1 setup you would have three identical surround speakers at the same height and same distance from the listening position. You can compensate for a rear center speaker that's closer to you than the others by adjusting the levels and delay timing. But, if that speaker is only inches from your ear, the speaker will not blend in with the other speakers, and in any surround setup, you want as seamless an encirclement effect as possible. Tonal mismatches, improperly set levels, and incorrect delay timing, create gaps and shifts in the surround effect. Using a nonmatching speaker in a jerryrigged position will only create a distracting sound, not a convincing surround effect.

With a sofa against the backwall, you'll have to resort to improvised methods of accommodating the rear center speaker, and every one of them (e.g. mismatching thin speaker, speaker right behind your head, speaker pointed down from ceiling, etc.) will likely result in a sound that's notably WORSE than sticking with a 5.1 setup. Just because your receiver has a feature on board does not mean that you have to use it at all costs. Focus your efforts on properly calibrating and positioning your 5.1 setup. You'll get lot more performance by doing that than by obsessing about jamming a square peg (rear center speaker) into a round hole (a room with a sofa against the backwall).