Yamaha DTXpress/DTXplorer/DTXtreme

Hi guys,

Usually when I practice, I use the preprogrammed songs on my 
DTXPRESS 1 module.  I mute the original drum part and I play my own 
beat to the music.  The sound is perfect while the music is off.  

Now here is my problem, when I press play on the module, the drums 
sound a bit muffled (less echo) than if there was no music playing.  
In order to get rid of the "muffle" i need to advance to a different 
drumset, while the background music is playing, then go back to the 
one that I was using.  While this solves the problem, it gets quite 
annoying going back and forth all the time.  Is there a way that I 
can make my drums sound like how they are whether the music comes on 
or not?

Regards,
Mike