Abstract: An impedance matching cable system for electronically coupling a musical instrument to an amplifier. The musical instrument has at least one signal output conductor and a common conductor. A field effect transistor (FET) having gate, source and drain electrodes is connected to a bipolar direct current voltage supply having a pair of voltage end point connections and a center point voltage connection by connecting the source electrode to one of said voltage end point connections, and the current control device connecting the drain electrode to the other voltage end point connection. The center voltage connection point is connected to the common conductor and a coupler AC voltage at the drain electrode to the amplifier.