4-Way Bi-Directional RCA Stereo Audio Switch, 1 in 4 Out or 4 in 1 Out, L/R Sound Channel Audio Switch Splitter RCA Stereo Switch Selector for DVD Stereo Speaker CD Player. Knob: 1 Selector Knob. ①It can easily switch four L / R analog sound signal sources to one L / R analog signal amplification device.
eBay