This is a remote RCA/3.5mm audio input for an Atmosphere AZM audio processor. The AZM will automatically detect the A-to-RCA-to-B jack and dynamically assign the appropriate audio settings, such as makeup gain, EQ, and automatic gain control, to that input. Stereo inputs are summed to a mono signal before being sent to the AZM. The Atmosphere accessory bus allows up to 8 devices to be connected to a single accessory port, reliably sending audio and data over 1,000 feet per port.