Decision time... replace poweramp or new powered monitors?

I was just faced with same issue, My 1972 Yamaha was starting to crackle. I was looking at power amps too, Most have fans. Then I was not sure about the newer class D amps. They seem to be what's inside powered speakers now. 
Trouble is everything has gone for multi channel surround systems now. So finding a plain old stereo amp is getting harder to do. Studio monitors are all powered now so not a lot of people making the amps for passive monitors. 
 
But I got lucky and stumbled on an old ( 1979?)  Technics Integrated stereo amp in the Goodwill for $29. It's in mint condition. Perfect match for my NMS10's. Bonus  it also has the speaker A/ B option so I'm going to hook up a set of small vintage Sony's for alternate listening.
The technics was a great find. The sound is better than ever, what a big difference. I didn't realize how primitive the old Yamaha was,, or had become? Obviously the power amp is very important when using passive monitors. 
So don't rule out older integrated stereo amps in your search. There still out there and nobody knows what there really worth anymore.