A PowerCube is a piece of equipment developed to measure an amplifiers output voltage. The method is based on discoveries made by the Finnish researcher Matti Otala during the 70’s and 80’s. A PowerCube generates a 3D graph of the measured amplifier’s output voltage relative to the phase and impedance of the connected load. Since the ideal amplifier would deliver a completely constant signal regardless of the load, the graph would be a perfect cube.
A PowerCube can prove that an amplifier is stable regardless of impedance of the load. Practically that would mean that the amplifier could handle any loudspeaker.
More information about the PowerCube and how to do PowerCube measurements is available at AudioGraph.