Mix output levels when drums triggered by MIDI

[tommi]

I want to play drum pads (a Yamaha DD 65) that play via MIDI into any software system (currently GarageBand or Logic Pro or Nano Studio in Mac OS X).
I can get it working so I can hear the sounds OK, but can't control the output levels via the mixer.
Any help appreciated...

 

[guitarplayr82]

Do you mean the mixer in the software program or a real hardware mixer?