Personally, I wouldn't bother with a 7.1 speaker set-up if my couch was against the back wall. you really do need some space behind the listening area for proper speaker placement, since the surround-back channel(s) should image from behind you.

However, if you're determined to go 7.1, here's a suggestion. Place the side speakers on the side walls, directly to the sides of the listening area. In yor situation, this will mean the side speakers end up in the rear corners of the room. Elevate them above ear level so that all listeners have a clear line of sight to the speakers.

Move the couch forward a few inches and place the rear speakers on the floor behind the couch, pointing up. This should bathe the back wall in a wash of sound. Will it sound like it's coming from behind you? Kinda, sorta. But, at the very least, they won't sound like they're coming from your sides. Not optimal, but at least you'll have some side vs rear (quasi-rear) imaging in the surround field.

I've only heard a set-up like this once, in the living room of a friend who insisted on a 7.1 set-up despite having his L-shaped sectional in one of the rear corners of the room. He had originally tried ceiling mounting the rear speakers and that didn't sound as good as spreading them out behind the couch.

Like I said, with the couch against the back wall, I'd personally stick to 5.1. With the speakers so close to the back wall, the tripole setting will probably work better than dipole. However, you should try them both ways, and choose what sounds better to you. After all, you're the one that's going to have to live with the set-up, not us. The resulting sound should be one that pleases you most. Experimenting with both settings is the best way to find out which one sounds better in your set-up.

Good Luck,
Sanjay

[This message has been edited by sdurani (edited September 25, 2004).]