Mitsui/MA-M is on par with the top of the line TY discs. I happen to prefer Mitsui's Colorado Springs-manufactured gold discs to both the TY and Mitsui silvers, but both companies' top silver models are cream of the crop for audio purposes.
If you are interested in advanced theory this article is very interesting: http://www.genesisloudspeakers.com/whitepaper/Saga_of_the_Black_CDs_v3.1.pdf
If you are interested in advanced theory this article is very interesting: http://www.genesisloudspeakers.com/whitepaper/Saga_of_the_Black_CDs_v3.1.pdf