For differential (i.e. fully balanced) amplifiers using one REL, simply use the standard connecting scheme with the exception of NOT connecting the black wire to a negative speaker terminal. Instead, it should first be allowed to “float” or hang down without connection to ANY terminal. Should hum occur using this method, please try connecting to an unused RCA connector on the rear of a preamp or amplifier. Please contact your dealer should there be any questions concerning this or any other hookup procedure.