Yamaha DTXpress/DTXplorer/DTXtreme

Thanks for the advice - I will try all you suggest.
Mostly I play with the kit set up on a concrete floor with the kick 
pad/pedal on a rug anchored under the drum stool legs (to stop it 
creeping) so it shouldn't be floor transmitted vibration. It did 
occur to me that maybe the kick pad is picking up vibration from the 
speakers which might cause rejection - still I'll try playing around 
with the rejection/velocity settings & see if I can cure it - thanks 
again.

R.D.