What exactly can be accomplished by changing the background color settings?
By setting the background color with rekordbox, it is possible to change the color displayed by the CDJ browse screen. This may be set individually for each USB device/SD card. By setting the background colors for multiple USB devices/SD cards, the DJ is able to determine exactly which USB device/SD card is connected to the CDJ at any given time. The CDJ display’s colors may also be adjusted to fit any specific preferences the DJ may have.