I am looking to purchase the SuperCinema 3D Array for my LCR. It will be placed on a fireplace mantle below my tv.

I am looking for in-wall speakers to complete a 7.1 system.

Would I use the Invisa MPX for all 4 or would that be too much? Or should I use the MPX for the rear surrounds and get the Invisa 650 for the rear back's?

Any help is appreciated!

A 7.1 System with four MPX for the rear/surround speakers would be an excellent setup. If you want to moderate a bit, MPX for surrounds and 650's for rears would certainly make good sense. The 650's have a square grille available for in-wall applications.