Big Krells Have Vanished From The Used Market

Big watts are unreliable due to heat. A friend used to own the larger FPBs and the amps showed leakage with the capacitors or some other components. The cost of maintenance may be high. Personally, I would not go higher than 200W for Class AB solid state amps. For higher power requirements perhaps look at some of the Class D options. Alternatively explore more efficient speakers.

"Big watts are unreliable due to heat."

Disagree. If properly and conservatively designed, hot running (class A) amps are very reliable.

Case in point, my Threshold SA6e’s from the early 90s are still running strong with never a fault. At 25 years of use, I replaced the power supply caps and rectifiers (both easily available from Mouser/DigiKey) as preventative measures.  And still going strong.

Wow I'm very very sad i only have 350W channel oh well!!!

Wow!, Ridiculous!, I have a modified krell fpb 700cx,  never runs hot because you have to use a single pole 30 amp breaker!, anyone who has a big krell that runs hot does not know what there doing!, as far as class d amp's,  listened to many,  still do not own one,  and yes, I'm holding on to mine for sound reasons,  my unit sounds a lot better than the stock 700cx 😉

They are few and far between.  I purchased a pair of fpb-750mcx blocks thru Audiogon a year ago (there were 2 sets available at that time - both in Canada) to replace a KSA-300S that wasn't up to the task of being able to properly jam the bass panels on my bi-amped Apogee Divas.  Each Krell has a dedicated 30amp wire; as do each of my Audio Research 610T's (upgraded to run KT120s), which run the highs and mids.  Many probably scratch their noggins over having this much power on hand, but I suspect those folks haven't heard the magic of Divas when properly powered.  My KSA-300S ran really hot and would actually throw its breaker...not surprising for what I was asking it to do.  The 750s do NOT run super hot like that at all, but they are warm.  Of course the tubes on the AR's are giving off considerable heat anyway. Luckily I have a separate Hvac system for my listening room, so it's not an issue for me.  Zero complaints about the big Krells.