Using an Interface

The recommended way to change DJ's is the really the most simple. Play a regular record (or CD) using the THRU on the virtual decks in Serato DJ. Once you have your track playing, unplug the interface from the finishing DJ's Laptop and into the starting DJ's Laptop. This method applies to the Rane SL2 and Rane SL3 boxes. 

Remember that the SL 2 & SL 3 require a power source for the thru function to work without a laptop plugged in, so make sure you have the additional power supply connected when you remove your USB cable. Your local electronics or hardware store will most probably have one. Check your interface to find out what voltage and current it needs. 

The Denon DS1 does not have a power socket therefore you will not be able to perform the transition as above. You would have to route the CDJ/Turntable with a regular track playing straight into the mixer and then swapping over the USB cable. Once swapped over, play a track in the virtual deck through INT or in DVS mode on the channel with the CDJ/Turntable still plugged in. You can now plug the other Turntable/CDJ back into the interface. 

This method also applies if you do not have a power supply connected for your SL2 & SL3 interfaces. 

For the Rane SL4 interface please read the instructions and watch the Changeover video here. 

Using a Mixer

If you are using a single USB mixer like the Pioneer DJM-900SRT the change over options are pretty similar to using a powered interface. Turn the input selector knobs on the top of the mixer from USB to the Line In/Phono/Thru inputs, and play your record or CD while you change over.

If you are using a dual USB mixer like the Rane Sixty-Two, Sixty-Four, turn the input selector knob on the top of the mixer to the channel that the next DJ's laptop is plugged into (i.e. A or B).

For the Rane Sixty-Eight, when both laptops are plugged in the Virtual Deck Vinyl Control dropdown menu will now have the option OFF (Changeover) appear. If you are the finishing DJ, click on that and this will free up that virtual deck for the next DJ. 

Using a Controller 

If you have a powered controller, plug an audio source into a spare channel or AUX input during changeover. You will not be able to do a changeover with non powered controllers.

If you have a controller with two USB ports, such as the Pioneer DDJ-SZ, its as easy as using the USB selector buttons at the top of the of the mixer section to change the channels between the two USB inputs.