How to dampen electronic drum kits.
 

Just got an Roland TD-4KP electronic drum kit. After barely a few hours of using it my downstairs neighbor is already complaining about the noise. Mind you I am using headphones so it's not being amplified. My best guess is that the kick pedal is the culprit since my neighbor says it sounds like I'm stomping on the floor. Any ideas on how to dampen the sound?

Apart from putting a rug under it there isn't much you can do.