Quiet fan to cool amp and preamp?

Radio Shack sells whisper fans for equipment. They usually come with bare leads, so you can wire them into a switched circuit or insert an in-line switch between the fan and a plug. The size and volume of air moved by the fan should be determined by your installation. Obviously, try to make sure the fan is powerful enough for your needs. If you're not going to cut a hole in the back for the fan, you will wind up recirculating warm air, so you may need a bigger fan or more than one fan. Also, the fan may generate some noise on the power circuit and in RF, so it might be desireable to plug it into an isolating power conditioner and to experiment with location to minimize RF noise. Are there any advantages to having the fan suck air in the front and exhaust it out the back? This would require cutting a hole in the back for the fan and locating the fan higher than the component versus lower than or directly behind the component if it were blowing onto the component from behind. Good luck.

I use two 4" muffin fans; one one each side of my amp drawing the heat *away* from the component. You do not want to blow the air directly onto your equipment. The above suggestion of cutting a hole in the back is a good one too. The fans that I have are high capacity 115 CFM & make a lot of noise at full speed, so I use a variac to reduce the speed to minimum required to keep things cool & they are very quiet. Right now they're running at about 90 volts. If you can tolerate very low airflow volumes then two fans could be wired in series. Or you can wire a power resistor inline to reduce voltage if you don't have a variac. Solid state motor controls are electrically quite noisy so that approach is not advised.

There's a fan in my integrated amp that is VERY quiet... I have to put my ear 3" away from it to hear it running. The fan itself is an "NMB" model # 4715MS-RT-B10.

directron.com sells pabst fans. they are only 12db.