I happened to have both M3B MM (used) and M3B MC (new). After realizing that the used sounds as good as the new, and the MC is not as quite good compared to Allnic H1202 MC and Hashimoto based SUT, I sold M3B MC.
I like to hear from anybody who had owned M3B and happened to upgrade it. Which preamp did they upgrade to? How much better the upgraded preamp is compared to M3B in sound quality?