I just discovered that the 47K loading is available for both the MM and MC inputs. I have a Supex SDX2000 which is a high output MC cartridge that expects 47K. Is there a difference from a circuit perspective when using the MM or MC inputs at 47K in this case? I obviously do not need the additional gain.
Actually, it is fine running at Medium Gain. I am curious since from the circuit board picture it appears that the MC circuit is separate from the MM one, whether that is optimized for MC cartridges in ways different than MM ones.
After thinking about it further, it may simply come down to whether one needs 60db of gain since the MM and MC ranges do not overlap. In trying to examine the board layout it appears that only the input stage is dedicated to each type, and that both get routed to the same passive EQ and output stage.