Yamaha DTXpress/DTXplorer/DTXtreme

I'm new here.  Just bought a DTXPRESS III last week.  I'm having a 
great time with it.  I have played bass for 15 years, but never 
drums.  So not only am I new to Electronic drums, and Midi, I'm new 
to drumms all together!

My question is:  What should I do about getting double bass?  Should 
I get a double bass pedal?  Should I buy another bass pad and figure 
out how to connect it?

The guy at the music shop strongly recommended a single pedal, he 
said he thought I would have a serious problem getting it to work 
with this kit...but others seem to be doing it.

For some reason having an additional bass pad apeals to me but I 
don't know if that is a possibility.  I did read through some of the 
messages here hoping to dig up an answer, but honestly a lot of it 
was over my head.  Any help would be appreciated!

Thanks!

Kayden
www.cultofodd.com