I haven't tried to do this (my stuff's in an old entertainment center), but the 770 will definitely need some air movement -- without some sort of vent, you effectively have a space heater in an enclosed space, and the temperature will rise steadily until it is a danger to the equipment. The 950 puts of comparably little heat, but still needs a little ventilation. In a totally enclosed closet with a lot of gear in it, I'd look at perhaps an undercut or louvered door and maybe a ventilation fan (something that could discharge hot air into an attic, for example).

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