Jmaldonado...As I said in a prior comment, at least one such preamp exists (Tandberg 3008A). There are just 2 gain stages and only a couple of resistors differ between the MC and the MM circuits so as to adjust gain. (Of course the inputs have loading resistors and capacitors as appropriate for each cartridge type). It seems to me that if you can achieve a good MC preamp it is a trivial change to cut the gain for MM use.
On the other hand Rauliruegas has designed his unit with different circuits, and different transistor types, because he feels that each type of cartridge should have an optimal design.
On the other hand Rauliruegas has designed his unit with different circuits, and different transistor types, because he feels that each type of cartridge should have an optimal design.