The Speco Technologies Stereo / RCA CAT5 Extender Unit pairs up with a second, identical unit, which is sold separately, to extend an audio signal up to 2000 ft. It features a selector switch for choosing between a 3.5mm stereo audio and L/R RCA audio input, and it automatically carries the selected signal up to 2000 ft over one CAT5 UTP cable. It supports bandwidths from 20 Hz to 20 kHz.
No configuration or power supply is required. All that's necessary is connecting the input and output cables and selecting the desired input.