There are lots of different class A circuit designs, but you can't go wrong with FirstWatt amps by Nelson Pass, if you have fairly efficient speakers. Reno HiFi will let you try before you buy too so you can hear it in your system. My F7 runs really hot, especially this summer on the east coast! But it is worth it, drives my 88db speakers very well and has a lot of the holographic qualities associated with tubes. Enjoy!
Ron
Ron