{HEAD ~ Resistors R} located between the non inverting terminals of op amps 68 and 70 to voltage sources V2 provide {TAIL ~ balanced impedences} to the op amp terminals 
provide
{ HEAD ~ Resistors R } located between the non inverting terminals of op amps 68 and 70 to voltage sources V2 provide { TAIL ~ balanced impedences } to the op amp terminals
HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH