Arturia DrumBrute - Headphones

1.7.5. Headphones
The headphone outputs carry the same signal as the Mix Output and operate the same way,
with one exception: When one of the headphone jacks is connected, the metronome will be
removed from the Mix Output but will remain in the headphones until its individual output is
used.
The behavior of all other connection options is the same for the headphones and the Mix
Output, including the metronome: When a cable is plugged into one of the individual outputs,
that instrument channel’s signal will be removed from both the headphones and the Mix
Output.
Arturia - User Manual DrumBrute - Overview 18