It's hard to say with the information at hand. It could be that alzy101's amps were plugged into a different circuit, or that their interconnects were routed differently than previous amps and got tangled in some power cords - hiss at a distance of 12" from the speaker isn't difficult to produce with cabling, particularly with high efficiency speakers (I've done it with my Paradigms, which are pretty middle of the road on efficiency, and fixed it with some wire management). I'm not sure what speakers alzy101 is running, but yaffstone has Klipshs, which tend to have very high efficiency ratings and are therefore easily susceptible to minor system effects. I will offer this bit of first-hand experience, though: I'm running a pair of M200's and a 750 (the 755's predecessor), and the amps produce no audible hiss even with an ear at the grille cloth.