I hate to say it but if you are in a smaller room that is really quiet, any fan is going to be heard. There is no way to kill it. I have tried.
Quiet Amp Cooling Fan
Can anyone point me in the direction of a VERY quiet fan that I could use to increase airflow over my amp? I know about the Parasound Zbreeze, which is now discontinued and also too noisy. A really quiet version of something like that which sat atop the amp would be fine or even a small circular fan which could be mounted to the vertical pole of my rack might do the trick. Any suggestions would be greatly appreciated.