Well I can only speak for my expieriance about Halos running hot, but with the A51/A21 that I audtiioned at Good Guys for over two hours and high volume levels, they did not run hot. They were in a entertainment style cabinet, front/back open, and 8 - 10 inches of clearance between units.
As all can see from my web pictures, my four A21s have ample clearance, and even at what most seem are high volume levels, none run any where near HOT. The one that is doing most of the work driving the front 80s, never gets to a temp that one can not place a hand on it, what I would call warm, yes, hot, not at all. Well having had the A51 here, it did not run hot either.
When we set the BFD up, Lee had a temp gun and checked the amp temps, but I do not remember what they were, perhaps he, Peter, or Adam will be of help on that.
