For my real job we use cabinets with built-in cooling with sensor for the computing equipment. They sit in DataCenters so we really don't care about the noise too much... These appear to be better suited to our needs for quiet operation in an audio setting...

Depending on your rack configuration it would my sense to work out the air flow. Perhaps utilizing 2 units. One for intake and one for exhaust.

I am curious Andrew...are you having overheating issues on some of the equipment? Even if not it will always prolong the life of electronics if you can keep a stable temp. It's the fluctuations that will kill ya...