The question as to what is different ???? Everything, and in every single regard !!! Keep in mind that our amps are mini-me Kraft's, but the 250 / 300's are just beasts !!!! In my lifetime I have heard 3 amps that I regard as the best, which are the Kraft's, the CAT sig's, and the Lamm hybrids....ss, tube, hybrid, and all are very similar...now, I also know Rolf, Ken, and Vladimir, and how they approach listening, tweaking and testing, and all 3 amps have been matured over the years, which to me is the real success of all world-class gear.....
As for Al...well, I have a used pair here that I'll upgrade for him to current status, and I promised him this pair a while back, but he knows that he has to wait a bit longer, as I'm still HAMMERED.......
Late,
Klaus