Have anyone experimentet with replacing fans on iTech amps?

As far as I’ve read they use very high power (and noisy) 70x70 and 60x60 fans.

The problem is that the fans are controlled from the amp via 4 wire cable: stable 12v, PWM and tachometric. If one replace the fan with a lower RPM the amp goes into protect.

Any idea how to get a good solution for replacing fans so the iTech can be used within the hifi/HT room??