I couldn’t find an output impedance spec on the C712, or anything that would provide an indication of how its balanced outputs are generated. But given that it is a solid state design chances are its output impedance is relatively low. And given that all of the input connections it provides are unbalanced, chances are that one of the two signals in the pair of signals it provides to its balanced output, for each channel, is generated by putting the other signal through a simple op amp stage, ca. 1995. Which in turn suggests that the C712’s unbalanced outputs stand a good chance of providing better sonics than its balanced outputs.
Given those considerations, I would suggest simply using an RCA cable having relatively low capacitance, less than say 20 pf per foot, and providing good shielding. Blue Jeans LC-1 meets those requirements at a low price point.
I suspect that will work out fine. If not, though, a Jensen transformer can be considered, as I mentioned earlier.
Also, FWIW, personally I would much prefer to replace the preamp and/or add a Jensen transformer than replace your amplifier, which is a treasure based on all of the user comments I have seen about it.
Good luck. Regards,
-- Al
Given those considerations, I would suggest simply using an RCA cable having relatively low capacitance, less than say 20 pf per foot, and providing good shielding. Blue Jeans LC-1 meets those requirements at a low price point.
I suspect that will work out fine. If not, though, a Jensen transformer can be considered, as I mentioned earlier.
Also, FWIW, personally I would much prefer to replace the preamp and/or add a Jensen transformer than replace your amplifier, which is a treasure based on all of the user comments I have seen about it.
Good luck. Regards,
-- Al