SUT vs. Phono preamp

On what basis is  the decision to chose  a SUT vs. a phonostage made?
Apart from the SUT or high gain Phono Stage there is a third option such as Headamp (or Pre-preamp).

SUT is passive
Headamp (or Pre-Preamp) is active device

If your MC phono stage can’t handle your LOMC cartridge or you’re not satisfied with the quality, you can use SUT or Headamp and MM phono stage.

You have to pay more attention to the amplification device if your phono cartridge output is less than 0.25 mV, if it’s higher then you may never need a SUT or Headamp and most of the MC phono stages have enough gain to handle your LOMC cartridge.

Still you may like different flavor of the SUT (or headamp) in comparison to the high gain MC phono stage.

As you know each phono stage is different, even of there is a gain for LOMC it does’n mean it’s better than another phono stage + SUT.

"Current-injection" MC phono stage for low impedance MC is something special, it can be much more impressive than conventional MC phono stage.

Noise is not the issue when you're using quality devices, no matter what type.
Normally with a Phono Stage you have optional loading for your MC cartridge and you can change it right on the phono stage. To do that with SUT you will have to change SUTs

if you really want to understand SUT’s, here is a reference for how they work and how to choose one.

personally i have 2 SUT’s right now (one with copper windings and one with silver windings) in my system i’m demo’ing. these guys.

the advantage of an SUT 'in theory' is lower noise, and 'in theory' greater micro-dynamics, than a head amp since the SUT is passive. in essence; a head amp involves an additional amplification stage which 'in theory' always will add some noise......and reduce the sense of naturalness and ease. as always; there are no absolutes; these concepts depend on degrees of execution. SUT’s are not always better, and head amps are not always worse.

it depends.....

I have 5  LOMCS, one phono preamp and one SUT. Actually, I do not notice much difference between  the phono preamp and the SUT, but I just wanted to know a little more about the theory behind all this; your responses so far  have helped  greatly. 

I had a Denon AU320 SUT teamed with my ZU-Denon DL103 and I didn’t particularly like the sound as it sounded kind of flat.  I sold it and bought a Bobs Devices SUT with the Red Cinemag transformers.  The sound was clearer and much more involving.  
What is your phono stage @boofer ?