I don't get why people are a bit off put about a amp that's a bit warm. That's actually good, it means the transfer of heat is operating properly. Now if it's scolding hot, then that may be perhaps an instance where the thermal solution is inadequate, and active cooling, or at the very least, passive heatsinks should exist. My favorite? A case design that makes contact with heat producing parts that is a part of the case itself is the best if you're going the passive route. Top vents are most ideal if there are going to be any vents if performance is concerned, though negligible if side vents exist at a similar height to the top panel, and it prevents from dust setting in the amp. That's one thing I hate about top vents like on my 789, just dust always falling in there. Bottom vents are meh, especially as the height of a case grows.
At any rate, the most important portion of all these temperature concerns, is looking up the specification sheets of the parts and their operational temperature limits. If they fall under such a degree, then all is well (though that would require thermal imaging of all the parts during operation with thermal probes). Besides this, I think all parts that produce localized heat should have some sort of thermal dissipation aided by heatsinks in some fashion. It's not an all emcompassing rule, but safe to say heat and power cycles are the death of many electronics (or at least exacerbated by it in theory at least)
