SUT Advice - Which Ones Are The Best?

I am currently in research mode.  I want to add a SUT to my set-up but I am finding that there is not a lot of information from my local audio shop resources.  It seems that SUTs are outliers in the high end audio world.  
That said, I have read several articles in magazines and the web touting their merits.
Of all the brands out there I am most familiar with Bob's Devices.  Art Dudley wrote many good things about his experiences with Bob's SUTs, and I happen to trust Art (God rest his soul), but I'm wondering if there are others I should consider as well.  Please post your recommendations if you have experience with any SUTs, regardless of brand.
As for my set-up, I have a SME 20/2 turntable, Tri-Planer tone arm, Lyra Kleos cartridge, and KTE LCR Mk5 Phono preamp.  I do not know if I will always use a Kleos cartridge but I do think I will always buy low output MC carts.  I hope to buy something that will work with low output MCs but have some adjustability just in case.
I'd love to hear your recommendations.
I have a Dynavector SUT, was hard to find, even harder to get documentation like a users manual (from dynavector that is) and expensive. But oh so nice, quiet, smooth, detailed and lush. Of course that’s with a Dynavector XX2, and run thru my McIntosh MX110Z. Highly recommended..
sokogear, I think you have a pretty good handle on the situation. Never heard one myself so only know what turned up after a ton of research. These things are transformers, very specialized transformers at that, and so they are more a way of tweaking or fine tuning the cartridge than anything else. There are whole websites devoted to the subject, with in depth reviews of far more different SUT than one would think even exist! Never even knew so many were out there until I started digging into it.  

This sets up the perfect situation for some to be able to say the SUT is essential and others to say forget it what a waste, and both be right. Because if you luck onto one of them that is really good for your particular cartridge and phono stage then boy oh boy will you be happy. But you could just as easily wind up with nothing or worse, a royal headache. 

The sensible approach I think is what Decware does, make a phono stage designed for high output carts, and then offer SUT in various gains to suit different MC outputs. You can also trade them back in for another in case you need to for cartridge changes. This avoids yet another pitfall of SUT, trying to sell for used something hardly anyone wants to buy new. Take a bath, you will!

If the phono stage has gain settings up to 60 or 65DB in addition to impedence selections for cartridge flexibility, why do you need an SUT? It would seem logical that more connectors introduce more distortion.

@billwojo summed it up nicely. The reason you "might" want a SUT is because it may sound better. Passive SUT vs active gain stages in order to get to the 60-65dB gain. Transformers have much more benign distortion characteristics than active circuits and are capable of producing a wonderful soundstage with detail and separation compared to transistor and op-amp alternatives. The main issue really is cost - transformers are incredibly expensive compared to transistors and chips. A complete MC phonostage is obviously more convenient than a separate transformer and MM phonostage. The MC phonostage made entirely with solid-state circuitry is way cheaper to produce than one with transformers.

In every case I have heard I prefer the SUT....but that’s just me, my gear, and my ears. To each his own preference.

Anyway you slice it... (whether it be pure tubed, SUT/tube, FET/tube, and yes even with some solid state devices, etc... ) I truly believe that we should try and remember that we, as vinyl lovers, should all feel thankful and blessed that we have so many great and talented designers who are able to provide us with a plethora of fantastic options that are available to us at so many different price points that it allows us all to have the opportunity to be able to enjoy the great sonics that vinyl can provide :)

I do not understand how anyone would be able to categorically deny the worthiness of a component that they may have never even heard in their own system, simply because of a certain capacitor, wire, passive/active device, etc... that is being employed. I’ve always believed that the worthiness of a component is a combination of the entire circuit design and the sum of all the parts working together seamlessly vs just one sole aspect of the component in question... not to mention the importance of system synergy.

We are all individuals, with our own set of ears, with our own unique way of hearing sounds. We all have our own set of listening preferences and sonic priorities. What is important to one, may not be to another. But, what we all "mostly" have in common is the love of music and being able to reproduce that in our homes :)

I know that it is the opinion of many, that in order to have a high gain phono amp that it must have to be a Solid State or FET design or else there will be just too much noise.  For those people I would suggest the Wavestream Kinetics Deluxe Phono Amp. I have admired Scott Frankland’s audio design work (phono, preamps, amplifiers) for decades but was never in a financial position to afford them. However, over the last couple of years, I have suffered 5 unexplained strokes and have recently been diagnosed with two cancerous tumors. I have come to realize that we may not get any mulligan’s in this game of life. 

So, on Feb 17, I placed a deposit with Scott for his most recent Wavestream Kinetic Level 5.1 Reference phono amp. His phono amp has always been on my "bucket list". It is an all tube design currently using (2 x 12AX7, 4 x 6DJ8); with extremely low noise ( I believe with the external power supply, noise is below 1uV (one-millionth of a volt ); providing 3 front panel selectable inputs = two MC at 62 dB of gain (without the use of SUT’s or FETS) with a useful cartridge range of 0.2mV to 1.2mV and one MM output at 42dB (you are able to choose your MM gain or you can have 3 MC ); having both balanced and RCA inputs and outputs; adjustable loading available on the back panel via custom loading plugs; and an essentially flat RIAA EQ curve within one tenth of a dB (.1dB) from 3 Hz to 40 Khz. *** The above specs are from the best of my recollection - if you have interest, please consult with Scott Frankland to confirm. He is wonderful to communicate with. ***

It is very dynamic, both in the micro and macro sense, throughout the entire frequency range.  It produces rich harmonics that are exhilarating when listening to violin/cello/acoustic bass, both reed and brass instruments, vocals, etc... all without sounding syrupy.  It is extremely quite, plenty of gain and very pure sounding... due to not having to use any FET or Solid State devices, no need to use Step Up Transformers and their extra set of interconnects and connections or having to fight with hum issues.

It is a very well thought out design, by an extremely talented designer and a true gentleman who is absolutely fantastic to deal with, Mr Scott Frankland.  I feel very blessed to be able to have this piece in my system.  At $9K new, I feel it is an absolute steel.  Once in a very great while, you might see one come up for sale on the used market, but not very often.  I consider this to be a true testament to the greatness of this phono amp as people who own it, hang on to it.  It is not a "flavor of the month" type piece, but rather something that you cherish and would like to pass on to your children.

In any case, just another excellent option to be considered :)

As for SUT's are concerned....  Not all SUT's are created equal.  There are some great ones, and others that are not so great.  I have a vintage Hirata Tango that has an exceptionally wide bandwidth with no ringing.  When used with some phono stages ( that are not up to the same refined standard of my Wavestream ) the Tango can absolutely improve the sound of those phono stages.  However, as nice as some SUT's can be, it is imperative that you match the SUT to your cartridge and phono stage.  You can't just simply use multiple different cartridges with a single SUT.  Just too many variables with gain, output, impedances, etc.  You also have to contend with additional interconnects, possible hum issues, etc.

Wishing you all the very best of health, love and happiness!

My Hashimoto HM-3 has recently been on loan to the HiFi Group I am a member off.
I missed a very recent meeting, where the HM-3 SUT was used in a demonstration with a Bespoke Built Head Amp.
The differences in the performances were reported on as a follow up in an email chain.
The Hashimoto has been claimed to have been mellow, relaxed and having a refined detail retrieval. 
I can concur using recollections of my experiences about the refined detail retrieval, I have noticed this myself when the SUT is in use.

The Head Amp has been claimed to have forward projection and airiness and incisive detail retrieval.
I can concur using recollections of my experiences, that when I have used a Head Amp in my system, the projection and clarity/lucidity of the presentation is noticeable and differs from a SUT in this area.
My experience with SUT vs Head Amp demonstration in my system will show a SUT to have a hint of Richness when compared to a Head Amp.
Are Mellow, Relaxed, Richness the same thing when different comments from different individuals are being offered about a SUT? 
Are Airiness and Incisive Detail Retrieval quite similar to clarity/lucidity when different comments from different individuals are being offered about a Head Amp ? 
Bear in mind another SUT 'might close the Gap' on the Airiness, but my experience is that SUT's add a hint of Richness, so the clarity/lucidity will be a harder gap to close in on. 
These are my thoughts on the matter based on my limited experiences.

If it is a must to get the presentation to meet the preferences of the end user and to be a satisfying long term experience, it is worthwhile experiencing each of the Designs (SUT vs Head Amp) to see how one is making an impact within a System.