Yamaha DTXpress/DTXplorer/DTXtreme

Pete:
I use the Behringer 602A to mix my two DTX modules it has four 
dedicated channels each with a three-band EQ. Two of these channels 
have a separate Gain control and the other two are stereo.

You could use this mixer in three ways:
1) Run a single line from the left channel to two channels, giving 
you EQ and gain.
2) run stereo lines from each of your modules into the two stereo 
channels, giving you EQ, or
3) Do as I do and hard pan your voices in the modules to extreme left 
or right and run four lines to the mixer. I run Bass (left) and Snare 
(right) on one module and Cymbals (left) and Toms (right) on the 
other. The Snare and Bass lines are run into the channels with the 
Gain control. This way I can tweak the sounds and volume of each 
grouping individually. Plus, when I record or gig out, I can forgo 
the mixer and send four direct lines to the console. A word of 
caution with this method, however, is that if you plug headphones 
into the mixer PHONE jack or couple the two DTX PHONE jacks together, 
the voices are separated in the left and right ears....it takes a bit 
of getting used to.

Stephen