Although the power output is low at 8 and 4 ohms, this line of amps can do 2 ohms just fine, and they can double their output at that impedance. So, this one can do about 340 watts per channel at 2 ohms, bringing the total to about 680 watts. This is a respectable figure, but still well short of the 1000 watts claim. Behringer for some reason likes to multiply their RMS output numbers with 1.4 (square root of 2?) to come up with the numbers they advertise. As for the fans, I suspect the fans are that loud in order not to melt the amp section when powering a bunch of subs in 4 ohm bridged mode.