David, a few years ago I did a considerable amount of experimenting with the positions of direct radiating speakers used as side(not "rear")surrounds. There appears to be an advantage with most sound sources(both movies and 2-channel music surround ambience with DPLII)to make them less "direct". It was found that pointing them inward toward the listener was the least effective option. Having them pointing directly forward on the back wall, preferably at least 3' above ear level to somewhat reduce the directness, was better. Still better was on the side walls about 1-2' from the back wall(for seating almost against the back wall)and pointed toward the back wall, to increase the proportion of reflected surround and ambient sound.
