I doubt that an external amp will make a difference in that small of a room with that close of a listening position. Unless your already driving your amp to clipping, in which case you're likely deaf or near deaf already.
That pioneer puts out quite a bit of power, and the amps are not "iffy".
Like mentioned already, if you need more bass get a good sub.
Klipsch RF-62II, RC-500, RS-400, SVS PC12+,
Def Tech SC8000
Harman Kardon AVR 1600
PS3, Apple TV, Sharp 70" Qattron