I have reviewed nearly all the amps mentioned above and the general run of remarks on Krell is reliable.
I have loan of current EVO 600M and find they run as hot as an old KSA 200 when on song, but they are very good, and still marginally prefer balanced drive (Transparent MM2) to Transparent CAST connection. But then I always have.
600Ms are remarkable, one of the finest amplifiers made and so they should be at the cost , typically £26k the pair UK. They are solid state but in the best sense of the term and are virtually grainless and free of colour, yet very transparent, at last a true winner over my beloved FPB700cx!
Martin Colloms Tech Ed , HIFICRITIC stereo magazine