Hello Everybody!

I currently have 2 qs8s, 2 m60s, 1 vp150 and 1 ep shake the hell out of my house 500.

I have about a 2 foot area behind my couch from the back wall. Would I hear a substantial difference if I went to a 6.1 or 7.1? My room size is 15 x 18 x 9.

If so, what speaker(s) would you recommend for the rear?

Thanks for your opinions that drive me to spend more money.

Mike