Yamaha DTXpress/DTXplorer/DTXtreme

I don't know if it the best way to do what you want, but you should edit a
new song and put the volume of all channels  to 0 except the channel 10.
Then link the QY70 midi output with the midi input of the DTXpress brain.
Link the QY70 line output to the aux line input of the DTXpress brain or
link the DTXpress phone output to a line input of the QY70.
Another solution would be to put the volume of the channel 10 of the QY70 to
0(or to mute the channel 10) and to send to the DTXpress brain only the midi
data through the channel 10.
Does it work?
vivien