Audio-Bus-Mixer

• sums the sounds from the
  Drum-Modules on the
  audio-bus
• two additional inputs
• lowest noise

http://acidlab.de/ProductAssets/Modular/Module_Overview.pdf

• 15 mA +12V
• 15 mA -12V
• ? mA 5V
• 28 mm Depth

No info about availability.