which is better ? MC phono stage or MM+step-up ?

MM phono stages introduce capacitance which is completely useless for MC carts. I am not technical enough to assess if capacitance would affect the sound adversely, so I would suggest looking into this and finding more professional advise on a subject.
Highly adjustable (mouse piano) phono stages,imho sound worse than non-adjustable phonos.

Brent, All transformers have a primary and secondary winding (if they only have a primary then they are called autoformers). The windings do not care if one side is at ground or not. So at the input to the SUT, you could lift the winding connection that is at ground, and use an XLR connector, set up with pin 1 (ground) being the arm ground and transformer shield, pin 2 being the + output of the cartridge and the 'normal' input wire to the SUT, and pin 3 being the minus output of the cartridge and the wire that was lifted from ground.

This effects a balanced input, and the output can then be single-ended or balanced, again using the same technique.

Ralph, I DIY'd the cable from the SUT to the mm section of my preamp first before doing any other changes. There was some improvement,but nothing like changing the tonearm wire and the internal wire of the SUT. My next move is to make a new DIY cable from the SUT to the preamp using the Mil-spec. solid silver wire.stay tuned.

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Emorrisiv, have you been playing with loading?

Right now I am loaded at 50 ohms and I like it pretty well. I have tried a lot of different load settings with my old MC phono amp and came to like it down around 200. I just got a old Dynaco Pas2 and after defeating the tone controls it is sounding pretty good. The secondarys are 1/15 or 1/30 and right now I am using the 1/30. Lots of gain! by doing the math it comes to about 52ohms. With the other secondary it comes to a little over 200. I have not made up my mind which I like better.

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