My big home theatre system (which I rarely use any more) is set up with large 19 racks, totally enclosed, fans on the bottom of the doors to bring in air, fans on top to exit the warm air (chimney effect). I was a bear to have these things (two, each the size of a kitchen refrigerator) installed and get the gear placed, fitted and wired. It runs from a 240 volt step down and is isolated from the entirely separate hi-fi in the same room. I do periodic clean-ups of the rack system occasionally, change or refresh the wiring, dust everything inside, etc.
But, for a serious audio system, I would think rack mounting would compromise things. Look at all the discussion we have about decoupling, mechanical and electrical isolation, etc. The racked stuff works fine for what I consider to be non-critical audio use, e.g. supporting sound for a projection video system. And it does a nice job of housing all the video-related gear- small video monitors, video switcher, scaler, video sources, and the audio processor and amps, including subwoofer controller, as well as some amateur recording equipment- mic preamps, compressor, etc.
I would never consider using it for my serious 'stereo.'