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

I understand there are passive SUT's and active (headamp) SUT's.
Which of the two is better ?
I have tried the MC-4, Bent SUT, Altec 4722 SUT and Lundahl SUT. All seems to work very good.
Can someone point out an active SUT ?

Thanks for the inputs

SUT= step up transformer. this is a passive device.The signal from a low output moving coil (lomc)is sent into the SUT and then sent to a preamp with a moving magnet phono section (RIAA). The low output is "stepped up" so that the MM section will have enough additional gain so that the lomc can be heard.

Pre Preamp is a active step-up with it's own power supply. These also are put into a moving magnet phono section,but these are amplified where as a SUT uses it's current to create voltage. Probably the best out there is the ZYX,which I understand is very good. But these are usually inferior.

Then there are phono stages that have enough gain to allow a lomc to play without a step up. These came about mainly because Preamps were no longer being built with moving magnet phono sections. The "phono stage" plugs into a line level source input on a preamp and is a active device. Many will have a moving magnet as well as a moving coil setting for the additional gain required of low output moving coil (lomc) cartridges.

confused?

No, SUTs are usually better than pre preamps. I have not heard one but the ZYX pre preamp, or also called "head-amp" is very good. Most of the pre preamps I have heard are not nearly as good as a good SUT. They tend to have hum and noise and a limited band width. SUTs,can also have hum problems, but it is usually a relationship with a ground or a cable.
It is best if you can keep the tone arm cable going to the SUT as short as possible and to use good shielded wire.
Check out "Bob's Devices" for tips on grounding.Bob is a super nice guy that is very helpful and offers nice SUTs at very good prices. he helped me with my DIY project and I didn't even buy anything from him.
how cool is that?

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I think one of the best pre-preamps out there at a reasonable price is the Hagerman Piccolo. Dead quiet and with a few judicious parts upgrades it is utterly transparent and beautiful to listen to. Now I haven't heard a lot of these but I did compare this to the famed TX103's and I came away feeling the TX103's were colored.