I can vouch for the NHT SuperZeros being able to fill a space that size since I have 5 of them in a slightly larger room and on about half the wattage of your AVR.
The SZs do not have a keyhole on the back so you will need some type of mount like an omni mount or similar. I have my LRs on some cheap, small satellite stands about a foot or so out into the room. They could just as easily be up against the wall too.
I use one laid over on its side for the center which works and sounds just fine.
Klipsch RF-62II, RC-500, RS-400, SVS PC12+,
Def Tech SC8000
Harman Kardon AVR 1600
PS3, Apple TV, Sharp 70" Qattron