I also have Klipsch RF 3's. I first had them hooked up to a Harman Kardon AVR55. Alot of sound for "only" 55 watts. I never recall hearing any noticable hiss.
I sold my AVR in anticipation of an upgrade to the 950/770 combo. In the interim, I picked up an Adcom GFA 5502 (300W x 2 @8ohms, 450W x 2 @4ohms). This will be for my Magnepan "music only" system. I'm using a Creek OBH12 passive pre-amp (for now).
I guess the point is, I now have an audible hiss up near the speaker that I never heard before. I'm not quick to blame the components...they're well thought of. I tend to lean more towards the Klipschs'...they are sensitive, and I'm throwing alot of power at them.