The 803D's have similar efficiency to my old Infinity Reference 60's. I was driving my Ref 60's with a Nakamichi Amplifier One which was only putting out 80 watts @8ohms, but the Nak had good peak current of 28 ampers (For reference, my room dimensions are 7.0m l x 5.0m d, with an open atrium, equating to a medium size room). The E460 will be putting out around 190-200 watts @8ohms with a damping factor of 200 which should have *plenty* of power for your room size imho.
