If the amp is getting so hot that it will burn you if you touch it then that certainly is not good. The Thiel CS3.6 do seem to be a pretty tough load for any amp but the 555 should be ok, it was a heck of an amp in its day. Maybe the Adcom is getting a little long in the tooth and you should start to think about a replacement. You could also think about something like this to help keep it cool.

Rick


"A fear of weapons is a sign of retarded sexual and emotional maturity." Sigmund Freud