I just bought a pair of R-51M speakers to play audio only in a 12x12 room. I am using a Sony STR- DE135 receiver rated at 100 wpc. I had to turn the volume all the way up just to hear an audible sound. I also have a pair of Polk S15's bought at the same time and the receiver had no issues driving them. I then tried my old Yamaha R-700 receiver 50 wpc and they did respond to it but had so much distortion they were unlistenable. Again the Polk's sounded fine. Any clues as what I should try before I take them back?
