Native Instruments MASCHINE MK3 Groove Production Studio (Black) - Manual (Page 609)

3. To select another destination for the Master output, click the first area under the level
meter and select the desired destination in the menu.
This is equivalent to setting the Output parameter in the MAIN section (see above).
In this Master/Cue channel strip, do the following to configure the output of the Cue channel:
1.
Click the headphone icon in the strip’s header to show the controls for the Cue channel.
Audio Routing, Remote Control, and Macro Controls
Audio Routing in MASCHINE
MASCHINE - Manual - 609