Sorry, didn't mean to jinx you!

I actually thought you'd get more noise from the water flow than the pumps.
Sometimes the hum from pumps is from the vibration with whatever they're on. You can always put a mousepad to try and dampen the sound. I know there are some for sale here:
http://www.cafepress.com/reefsanctuary.11804268
Don't know much specifically about the Gen-X pumps, though.