I have two crown amps, with fans - I have never heard the fans (I have been using them for over 10 years now)
Keep in mind that the fans are thermostatic - and the amp is rated for 440W @ 8ohm - I use at most 16W peak... so the amp barely warms up, and the fans have never become audible (I don't know whether they turn off at a certain temperature, but I do know they are supposed to speed up above certain temperature.... something that I have never reached!)
Others have reported being able to hear the fans...
Do you have these crowns? The crown 8|300s have loud enough fans to certainly hear. They are nearly always on, because the amps themselves pull a bit over 200 watts at idle (each), and that heat has to be removed from the small chassis. They do change volume in the fans as the fan speeds change with thermals, but in my glass covered front AV rack (with fans in the back top for cooling), they are quiet enough to not be obtrusive because of the front panel, but I can certainly hear them in my room between tracks at a very low level. (Think something like a projector fan level when in my rack, behind the front glass). I agree with the previous poster. Most would not want these open air in the same room as your audio experience. They are too loud for that.
When I didn’t have them in my rack and they were sitting on top of my rack in open air they were still not quiet — my point is they are never silent one on and warmed up, even at idle. Both of my 8|300 make the same amount of noise, so if you are looking for a silent amp, these are not that.
My two Crown 8|300 together are louder than my four iNuke DSP 6000 together.
Here is a video showing the fan noise with the door open.