Hey - You may know this/maybe I misunderstood, but when you say "Hughes & Kettner 36 gets unbelievably hot, even when attenuated to 1W or 5W." -- You are actually gonna be much hotter attenuated as you are turning power into heat.Holy crap! My Hughes & Kettner 36 gets unbelievably hot, even when attenuated to 1W or 5W. You literally cannot leave your hand on top of the amp for the heat of it. I'm waiting for the video of someone frying an egg on a H&K tube head. Every component has a combustion point, and I'm betting some of them are getting pretty close.
I've been using a couple H&K 36s ever since I stopped lugging my Marshalls around. Very versatile little units. Surprised you don't see them more often. Admittedly, they can be a little fizzy if you don't watch your settings. I usually run them @ 18 - as I find the lower wattage settings choke the tone a bit for my liking.
If you have not put the TM36 thru a nice 4X12 - do it when you get a chance - You won't believe the tone - esp if you are typically running them thru the H&K 1X12 or 2X12. That would be the best time to get it towards dimed - for a test - you know - for science.