I have two Pioneer Elite M91 power amps and a Krell KSA-250 in my HT system (the M91s are used for the center channel and surrounds). I have also used both amps (bi-amped in the case of the M91s) in a stereo system with B&W 801Ns. Sure, the M91s look very pretty, no where near as good as the Krell sonically. The Krell is cleaner, more powerful, extremely dynamic with amazing bass control. Even my wife and daughters could immediately tell the difference between the M91s and Krell, they hands down preferred the Krell. How the M91s (or M90) compares with a modern day SS amp, I have no idea. My M91 are 15 years old and have never really given me any trouble, other then the power-on meter lamp.