If your doing it right, when the sound is up you shouldn’t even hear the fan noise. When I was running the QSC's you didn't hear the fans because they were hardly ever on, the amps being 350W per channel and typical listening volume on the 330's is 35W. So they were only running at 10% output, which I did because the more head room you have the less the transistors have to push and pull equaling less distortion, and there was very little distortion.