Can you put a Krell in an apartment?

I would not be that comfortable buying a 30-year old solid state amp.  Many of the components, like the output transistors, may be hard to replace if they go bad.  Tube gear is quite different in that most of them can be relatively easily serviced and stuff that is 60-70 years old don't give me much concern.  

If you are now considering alternatives to the Krell, it would help to know about the rest of your system, that is, if sound quality is of some importance.  

I don't quite understand going to extremes to fit in one piece of gear instead of looking for something appropriate to the system and the venue.  A small apartment should mean looking for suitable speakers and then electronics that work well with the speakers.  I cannot imagine why some high-powered behemoth is suitable, even if the speakers are notoriously inefficient or need some juice to come alive.

Boulder 850s ( now discontinued) might be a great "apt. amp'   Small 40 lb boxes, run cool, I think they sound great with proper preamp .

They are rated at 200 w/ch but fight above their weight.  Some people find them to dry but I prefer the power amp remain neutral and adjust the tone of the system via, front end componets and cabling.

Look around. They pop up used now and then

I’m sensing you going against all instincts here and getting the amp... I’ve done that before too. Makes for a longer road (and $$) than expected to get where you're ultimately meant to be. 

Krell will service the amp for 1500 bucks. If I buy It at 3500 I will be in it 5 grand. Do you think any 5 grand amp new will be as good?

I don't know about the specifics of this amp, but, something that old that cost so much back then would be astronomically higher in price in today's market.  I doubt that there have been much technological advances in amp design that this amp would be easily outperformed at this price level.  Of course this is all contingent on the amp being in flawless condition. 

All Krells run hot, and heat always shortens the life of components.  If this has been a heavily used amp, it might not be worth the price of purchase and refurbishing.  There really is no way of knowing, so it is a bit of a gamble.  It is good to hear that Krell can still service the amp, that is not always the case with old solid state gear.