I have a couch that is against the wall and a 5.1 system. I read that one can put monopole speakers to the left and right of the seating position. My question is, how high should they be placed? Most places seem to recommend 2-3 ft above the listening position, but thats when the listening position is not up against a wall...mine is. Should I still put them 2-3 ft above the listening position to my left and right? again, they are monopole.