VirtualDJ
Have your speakers connected to the rear-panel of the XDJ-RX3 and click "XDJ-RX3" for VirtualDJ to apply the pre-defined audio setup with the built-in sound card of the XDJ-RX3 You can still change that from Settings->AUDIO tab. Select the Software Control mode from the XDJ-RX3 if the relative message appears. The unit is now ready to operate.