Connect Traktor Audio 2 MKII with your computer using a standard USB cable
Connect your speakers to the MAIN Output 1/8" socket
Connect your Headphones to the PHONES Output 1/8" socket
Apply a Master & Headphones Audio setup in VirtualDJ as shown below. This setup is pre-defined and offered from the special TRAKTOR AUDIO 2MKII button in the Audio tab of VirtualDJ Settings.
Use the PHONES right-side rotary to adjust the Headphones Output Volume.
Use the MIX left-side rotary to blend Master Output signal and the PFL-enabled VirtualDJ decks to the Headphones Output.