I have MG 20's, and for the longest time was using a pair of Krell 300 MDA monos. Before that I blew up several HT recievers trying to feed these current hungry beasts.
I've used a pair of Fisher 80AZ monoblocks, and am currently using a pair of Dynaco Mk III's.
All of the above get hot to the touch, but I've had no failures running them 8-10 hours at a time.