The JOIN function on the SL-9000 transfers the Audio input select buttons (TUNER, CD, TAPE 1, TAPE 2, etc.), located on the bottom of the remote control, and moving them to any top Device button (AUD, CD, DVD, etc).

One purpose enables you to use Device buttons for multiple uses. Once the JOIN feature has been utilized, the press of a Device button will bring you to the respective device, as well as automatically selecting the Audio Input Select you joined to the device button. This is considered a mini-macro.

Another purpose of utilizing the optional JOIN feature is to give you eight extra buttons to use in the Audio mode. Once you JOIN an Audio Input Select button to a Device button, that gives you a free button to use for something else you may want to implement in its place.