I have owned several Krell Amps over the years and have never had an issue with any. My Fpb400cx Amps work wonderfully with my IRS Betas.
Big Krells Have Vanished From The Used Market
Once upon a time several years ago, you could always find several of the big Krells for sale on Audiogon. I'm talking the 500-750 wpc big irons. Now since Krell no longer makes anything bigger than 500 wpc, anyone with the 600, 700, 900 wpc amps are holding on to them because there's nothing new by Krell to replace them with.