Yamaha DTXpress/DTXplorer/DTXtreme

Great that you're getting the DTX power supply!

In the mean time, did you try playing the DTX's internal songs? Are 
they also low in volume? If the internal songs are at a good volume, 
thie will give you some more clues to the power supply and output 
stage of the module.

So this seller didn't give you any clue as to the working condition? 
I'm a little supicious about him not sending the power 
supply...accidentaly on purpose maybe? Hmmm... time will tell. 
Again, try the internal songs (with the headphone AND the L/R 
outputs), and good luck with the power supply!

Steve