Low heat alternative to FIRSTWATT J2 ?

The J2 and F7 are the two I am considering.

The reason the First Watt sounds like it does is its class A. Class A makes more heat; you're not going to find a cool running amp that is class A, so if you like the sound I would find a way to deal with the heat. Putting it in a refrigerator BTW will not work- the refrigerator has to get rid of the heat and will do so via its heatsink system.

One simple solution is to have a vent placed in the room above the amplifiers locations. The vents are then ducted to a fan that blows the air outside if needed. This system can be very effective and is cheap.

I would hire a cute girl to fan myself and the amp before I got rid of my F6 .

I would think as long as you have the amp on a simple floor amp stand you would be fine.  

It’s a simple thing to wire a small quiet fan hidden near a hot amp. Years ago I had amps in a closet space and did just that and it worked…there was a brand called Whisper Fan, now there’s lots of stuff for that. An easy solution that should help even in the smallest dwellings.