thanks everyone for the input. Let me add some clarification too:
The compartment that holds the power amp is ~24"h x 22"d,x 20"w. The amp sits on a shelf in the center and there is ventilation under and over. The back side of the compartment is open, but there is a glass door on the front.
I have had a B&K St140 running in it for the past 3 years and heat of the kind Atmosphere mentions has never been an issue though the 140 does idle slightly warmer than I would like, so I would turn the whole rig off when not in use.
In an effort to radically simplify for my wife's use, I want to leave the amp and preamp on 24/7. This way, she just turns on the tv, and the tv remote adjusts the volume. (Seriously, adding one more device to the turn on equation adds 5 orders of magnitude difficulty) If we will be away for any length of time I will simply switch off the rig.
I swapped in a lm3886 chip amp for a couple of weeks (zero heat at idle or running) and it was perfect heat wise, not so much sonic wise. For now the St140 is back in place and I'll keep an eye on the heat. I would like to improve on the sonics of the St140 though, and with low/no idle heat.
The Sunfire auto signal turn on is an appealing feature. I started looking for an outboard device but so far no luck.
