[Phlogiston]

I put a small 12V fan on the back of my tube receivers/amps and run it at 6 - 9V. It keeps the whole thing cooler and at reduced speed (6 - 9V) does not make much noise. The room will still get warm.

Sort of hard to make out here. The wall wart is plugged into the switched outlet so the fan turns on and off with the amp. This is a fisher X-100.