Csi3 as rear Center

DaveJo

I have an extra Csi3 would it work well for a rear center channel.

If so where do you hook a rear center to on the AVR. (Onk TX-SR800)

The Doc's say its a 7.1 capable receiver.

also, I have my Fxi3's hooked up to the surround posts but I have a second set that say "surround back/zone 2" would this be a better place to hook them up?

any help would be great.

Thanks