recommendations for amplifiers that don't emit tons of heat

Trig you fail to mention what is your budget and what is the rest of your system. 

There are tons of modern amplifiers which will best a  Krell KSA 150 it depends on system matching to what amplifiers will work for you.

We have the Nuprime ST 10 which is a 150 watt compact analog switching amp and it sounds fantastic much better than most Class D amplifiers and it is tiny and gives off much less heat then a big Krell, the bass conrol on the Nupirme is fantastic. 

Howerver that amplifer will not sound as good as many of our larger more conventional amplifiers. So again it is going to come to budget. 

The best amplifier in the shop a T+A PA 3000 gets warm but never super hot and that amplifier will run rings around Dan's newest designs. So it all comes down to level of performance you want to get and how much you are willing to pay for. 

Dave and Troy
Audio Doctor NJ

I can strong recommend two amps. The B.M.C. M2 monoblocks have fans but very  quiet ones. In balanced XLR and the Koda K-10, they are great!

The other is the H-Cat X-11 amp with automatic focus. It has heat sinks on back. I live in Texas and have had neither of these amps heat up my room.

@audiotroy
I posted the other components and budget, but not in the original post. I didn't originally post the rest of the components because I'm hoping to change the speakers when/if I can get into a larger room. So, while I realize matching to the speakers is important, they are a potential variable. Sorry for the confusion.

My preamp is Audio research ls27 and speakers are paradigm
studio 40 v4... the rest is Rega p9 turntable, dynavector 20x2 L, Audio Reseach ph6 phono preamp, and Cambridge Audio CD player.

My budget is $2000. I prefer used in the interest of maximizing value.
Thanks for your advice!