Paul,
I really think that your concern about heat generated by the JC-1s is a little overblown. I had them running hard for 4 hours last weekend, and at the end of it all, they were a little more than warm. This, by the way, was with the rear switch in 'high' Class A mode, where heat should be at a maximum. They don't produce anywhere near the temps that, for example, my Rogue Zeus did. Having said that, I note that the 3" clearance could be a problem. Is the quoted clearance above the amps, to the sides, or both? Parasound makes it clear that 6" is required above the amps.
One amp that I considered was the McCormack DNA-500. I traded numerous emails with Steve McCormack and was thoroughly impressed by the guy. First, the amp itself should run very cool. Second, those upgrades of which you spoke were designed to bring his previous designs up to his latest thinking. There is no upgrade available for the DNA-500, nor is there one planned. My understanding is that he believes that this unit is just about as good as he can make it at a reasonable price point. As for the cost of the upgrades on older units, if Classe decided to offer something similar, I assure you that their own prices would be high as well. Newer, high spec parts are expensive, and upgrades such as this are generally labor-intensive. Instead, they - like most - simply offer new models. I, for one, applaud Steve's long term support of his creations. In my opinion, you could not go wrong if you decided on a DNA-500.
