To use multiple CDJs as sound devices on Mac OS X, you must make certain settings, as described below.

01: From "Macintosh HD", select "Applications" → "Utilities" → "Audio MIDI Settings" to open "Audio MIDI Settings".

02: Select "Audio" → "Open Device Set Editor" to open "Device Set Editor".

03: Click "+" to add a device combination.

04: Check the checkboxes of the devices to be used, then click the Complete button.

05: Start up Traktor, then select "File" → "Audio Setup" to open "Audio Setup".

06: Set the above device set for "Audio Device".

07: From the Preferences menu, select "Output Routing", then set the above device set for "Output Channel".

08: Click "Close" to close "Preferences".