Please help before I start cutting up speaker wire! The Screen is on the 20' wall, and I sit about 15' behind it. Should I put the rear speakers to the left and right of me facing each other (like the Onkyo manual says), on the wall behind me (a good 10' back), or somewhere else? The other issue is that how the room is shaped, I would have to mount the surround speakers about a foot or two in front of me to get them on the walls - will this make a big difference? Thanks in advance!