A plug connector is disclosed that has a body portion and a circuit card extending forwardly of a mating face of the connector. The engine is a linearly reciprocating piston in a closed cylinder driven by pressure differentials between the gas on either side of its piston, the differential being controlled by a switching valve which directs higher and lower pressured gas to the appropriate side of the piston, and which recirculates spent gas from the lower pressure side of the piston back to the pipeline. A method for preventing a power domain having a lower priority from being turned OFF when a circuit having a high priority is turned ON is also provided. Acoustic power received by the input port is divided between the acoustic waveguides such that it is delivered to the aligned output ports to simulate a line array of acoustic power sources.