Native Instruments MASCHINE MK3 Groove Production Studio (Black) - Manual (Page 697)

Any audio source plugged into the first input of your audio interface will be available on the In 1 L input of MASCHINE, and
so on.
See ↑ 3.7.2, Preferences – Audio Page for more information on the Audio page of the Preferences
panel.
Using Effects
Applying Effects to External Audio
MASCHINE - Manual - 697