Apparatus for providing electrical power to signal conditioner circuitry inside a musical instrument having a signal output jack mounted thereon to carry a conditioned music signal via a signal cable to a remote location. The power source is a battery mounted inside a housing that is part of a signal plug on the signal cable plugged into the signal output jack. The battery powers the signal conditioner circuitry while the signal plug is in the jack. The housing provides access to the battery. Alternatively, a rechargeable power source is mounted inside or otherwise on the instrument and is connected to the jack. A power supply first plug is inserted into the signal output jack to charge the rechargeable power source. After charging the power source, the first plug is unplugged and a second plug of a signal cable is plugged into the jack to carry the conditioned signal to the remote location. When the second plug is plugged into the jack, the charged rechargeable power source provides power to the signal conditioner circuitry.