Pro Intercom AD903 I/O AdapterThe AD903 allows the connection of almost any other audio device, input or output, to a cabled intercom system. Typical applications include: 1) feeding the signal from a stage microphone or audio mixer output into the intercom system so that intercom users can monitor the program from a distant point; 2) feeding the intercom conversations out to an audio amplifier, and; 3) connecting the intercom system to another intercom system which is operating