I connected this to a vintage 1970's Kenwood stereo amplifier so I could remotely switch the inputs. I did have to source 5 volts to the internal circuitry from a usb wall wart to power it up. Works great in that capacity. I can switch any 1 of 4 stereo sources to the amplifier input. Doesn't introduce any noise or distortion. No switching noise, no dirty contact sounds, perfect. These things are very economical also.