The Pass and Krell will probably chase you out of the room in the summer. If you can find newer designs from both companies around the same price, I'd shoot for those as they'd last longer and(supposedly)sound better.
Amp upgrade ?
I have a handful of amps in mind that I would like to upgrade to but I can't decide, #1,pass aleph 1s #2,Krell KSA 250 #3,Bat vk-500 #4,Sim w-5 #5,Mark lev 23.5 my current system is B&W 804 pre is audio research sp 16 cd player sony scd-1 I have heard all of these amps but in different system configurations even though some are much older than the others I think the krell and mark are still good units.