can anyone explain the difference between all of the ports and slots mentioned in the programming manual? i dont have an installation manual so if its mentioned there, i didnt see it. basicall im just wondering if there really are diffent ways to connect an music source ( most likely a cd changer ) to provide music on hold, and background music to the station speakers. i see that there are RCA type connectors on the control board. but the manual mentions a couple of devices where i could route my music through. i guess i dont have all of my modules and circuit packs straigh, so if someone could briefly identify those that would deal with music and paging connections that would help me out some.