You could always disconnect the speaker wire at you main speakers and connect it to your center/surrounds to take a measurement of these speakers. You receiver will use its bass management circuitry. Easier than getting in behind a cabinet and changing plugs.Thanks again, John. I do have discreet inputs, but due to the electronics being in an entertainment center, they are almost impossible to get to. I will settle for the mains and sub for now. I may use the optical out just to take measurements.