Yamaha DTXpress/DTXplorer/DTXtreme

Hi guys!
Last night I had my first official complaint about the noise I was 
generating while playing my DTXPRESS. And to be honest I am not 
surprised as I have been concered about the noise produced by the 
kick tower while I play. Its not excessive as you know but seems to 
be enough to annoy the girl below. She didn't complain verbally but 
when I felt my bedroom floor shake as a result of her stereo I took 
the hint and put my sticks away.

Basically I want to inquire if any of you have recommendations on how 
to dampen the noise without affecting the performance of the kick 
tower. At the moment I use a standard felt head beater on the bass 
pedal. What are my alternatives? Would a rubber beater help? My 
bedroom floor has a old stle wicker/ropey carpet and I have put a 
carpet tile under the tower also.

Any help greatly appreciated,
Cheers,
Brian (london)