I have owned the Krell for six months. It is a great amp. With proper system matching, the right cables and speaker placement, it is a steal at $2500. I believe it is difficult to know the qualities of a component unless you have lived with it for awhile and played around with the variables. When I first purchased the Krell, I had an Adcom gcd750 and was looking for new speakers. I auditioned a number of speakers in my home and ended up with Aerial Acoustic 6s. I then played with cables and interconnects. The results varied a great deal, and at times it was frustrating. I settled on cardas cables and jenalabs interconnects. I cannot speak for the other amps you mentioned based on my statement about living with a component, but I can tell you that when it comes together, it is very rewarding and I enjoy my setup everyday. My guess would be that if you take your time and match components carefully, you won't go wrong with any of the amps. If you don't, none of them will sound right.
