I'm not familiar with MacCormack amps, but maybe someone with a DNA225 will chime in. The behavior you describe isn't at all unusual for power amps though. I had an Ayre V-3 that ran too hot to touch. I was speaking with Ayre tech support once and the guy said that's how they should run . . . "hot is good" were his exact words.
As for the rack position - I prefer to keep amps that run hot out (there are amps that run cool too) in the open (ie on amp stands, not in an enclosure), but as long as your rack is as open as you describe this may not be an issue. I would keep 2 ft above it open.
It's also not unusual for it to trip a breaker - especially if you have other equipment powered by that circuit. I imagine the amp is drawing maybe close to 10 amps on startup. If the amp is the only thing on that breaker - it may be worth checking out the amp again though.
It's worth a call to tech support, but it's possible this is all entirely normal
As for the rack position - I prefer to keep amps that run hot out (there are amps that run cool too) in the open (ie on amp stands, not in an enclosure), but as long as your rack is as open as you describe this may not be an issue. I would keep 2 ft above it open.
It's also not unusual for it to trip a breaker - especially if you have other equipment powered by that circuit. I imagine the amp is drawing maybe close to 10 amps on startup. If the amp is the only thing on that breaker - it may be worth checking out the amp again though.
It's worth a call to tech support, but it's possible this is all entirely normal