now that I am really enjoying my Axiom setup, I'm itching to get the full experience from my new SC-55. I want to add surround back speakers. I have a small wall abouit 5.5 feet wide, four feet behind my sitting position. It is centered fairly well in the environment. Should I get another set of QS8's or go with something like the on-wall M3's? Any advice?

M22v3;VP150;QS8;Hsu VTF3-MK4 sub