My setup is also similar. My QS8s are on the side walls about 4" from the rear wall and 24" from the ceiling. When I'm on the couch the center of the speaker is (horizontally) about even with my head.

And they sound great!

snazzed

M22, VP150, QS8 <--all v2
Sub: Outlaw LFM1-Plus
Denon AVR1910, Sony X900-65"