"RCA JACK INPUT TYPE,I/P IMPEDANCE,SWITCH ON: 11KOHM PORM 10PERCENT; RCA JACK OUTPUT TYPE,O/P IMPEDANCE: 470KOHM PORM 10 PERCENT; ITEM SUMS 3 AUDIO O/P FROM DIFFERENT VCR'S OR OTHER AUDIO SIGNAL HAVING SIMILAR CHARACTERISTICS TO SONY LINE OF VCR'S; THE EXPECTED VCR AUDIO O/P LEVELS WHICH ARE I/P TO THE SWITCH BOX ARE 250MV INTO 10K OHM LOAD,HAVING A 1K OHM O/P IMPEDANCE"