Native Instruments MASCHINE MK3 Manual page 643

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 ↑2.6.2, Preferences – Audio Page
Preferences panel.
for more information on the
Applying Effects to External Audio
Audio page of the
MASCHINE - Manual - 643
Using Effects