Rock, you don't indicate how far back the wall will be from your listening position. If it's just say 2-3', it would be little different than being on the side walls slightly farther back than your ears.

If it's farther back, your might experiment with having the surrounds tilted outward, firing toward the side walls to give some reflected sound as if they were on the side walls.


-----------------------------------

Enjoy the music, not the equipment.