SOFTWARE VS HARDWARE MIXING
The Denon MC6000 offers 2 modes for it's USB Audio Output bus selected by the switcher (B) at the rear side of the unit.
These modes can be selected/switched without re-launching VirtualDJ or power cycling the unit.
Default VirtualDJ audio setup will use "Software Mixing" ( Master /Cue or PC Mix) modes.
In this mode 4 decks mixing is possible, and all audio mixing is done by VirtualDJ itself.
The second mode ((CH2/3 or INT Mix) allows the audio from VirtualDJ to be send directly on Channels 2 & 3 of the MC6000 mixer. In this mode the audio mixing is done by the MC6000 hardware mixer, and only 2 decks mixing is possible. In order to use this mode you need to modify the default audio setup as follows:
The Denon MC6000 offers 2 modes for the USB Audio Inputs selected by the switcher (C) at the rear side of the unit. These modes can be selected/switched without re-launching VirtualDJ or power cycling the unit.
Due to firmware limitations and driver stability issues only REC OUT/MIC mode is supported.
In this mode the Default Audio Setup of this unit allows you to Record the audio produced by VirtualDJ. The result recording file is a digital copy of the mixing done via VirtualDJ as it's send on the Master Output of the Denon MC-6000.
Since the MIC audio is not part of the digital bus interface (MIC audio is not processed by VirtualDJ) the result recording will not include the MIC sound.
If you want to include MIC sound on your recording, or you opt to use the HARDWARE 2 decks mixing mode mentioned above, you need to modify your audio setup in order to include a Record input: