I am about to modify my Marantz CD94 (not MkII). I already bypassed the SAA7320B/P and installed DIP sockets for the opamps. I just quick replaced the NE5534s to OPA134s for now. The next step will be to get rid of the second opamp, that is an unity gain filter. For the I/V opamp I intend to use OPA627A and I want to try biasing it to Class A. Studying the schematics I came across something interesting: there is a resistor at the output of the DAC. It is connected to an +5.6V Zener diode through some resistors, so I thought it was for supplying the 2mA idle bias to the TDA1541A chip. However, the calculated current is only about 0.6mA. What could be the real purpose of these resistors? I attach the part of the DAC that I am talking about.