SUT With a Manley Steelhead RC?

I've never understood why one would put and SUT in a phono stage which already has a lot of gain, unless you just want it louder. 

It’s a complicated question, because the steelhead’s "Z" inputs uses autoformers (primary only) rather than a traditional SUT (primary + secondary windings). I don’t think most of us have a good understanding of autoformers in this application lol. I’m not even sure anyone else is using them here.

The description on Manley’s site is fairly good but still kinda hard to parse out. It sounds (perhaps) a bit more like a "current injection" head-amp in electrical function, versus a traditional SUT - where the "optimal" level Manley speaks of is going to be loading the cartridge pretty heavily (and that’s OK).

The "rough" gain range listed of 3 - 12dB is much lower than most head-amps and SUTs, but the extremely high "base" Steelhead gain (up to 65dB) covers for that.

If you get a SUT - it’s going to sound different than the autoformers, that’s for sure. Even SUTs can sound wildly different to each other! All you can do is try a SUT and decide which you like better. If you do, the SUT should be run at the lowest gain level (50dB) on the R input set to 47K and minimal capacitance load (0 is fine). Even 50dB is quite high, so you don’t want to push past the usually recommended SUT gain ratio for your cartridge. For an MSL Platinum at 0.5mV, I think a 10x SUT would be perfect here.

The "Sky" SUT Bob sells is excellent, and in your shoes - yeah I’d give it a shot against the Manley’s autoformers. The "Sky" has a warm, vibrant, rich sound with superb dynamics and big bass response. It’s not as refined or nimble as some of the other top tier SUTs (more expensive), but it’s a fun listen. Fantastic for rock. It really reminds me of a classic tube amp’s sonic style. And it absolutely clobbers the cheaper SUTs (entry level Lundahls, CineMag 3440A) IMO. My main complaint is the little metal boxes can be microphonic and they're also easily bullied around by stiff cables (both solve-able, but a PITA).

@mulveling Thanks for your reply.  If I do buy an SUT it will probably be the MSL model, since it's made for their cartridges.  I've spent less money that that on a very good phono preamp so it's hard to justify, but it's an itch I've had for a long time.  I also have to buy a good RCA phono cable to link everything up.  It sounds like I'm trying to talk myself out of this, eh?  

@artemus_5 I can see what you mean, which is actually why I asked the question, but I'm always interested in squeezing out more performance from my analog setup.  I have never tried a SUT, and have heard many good things about them in reviews I've read.  Art Dudley often wrote lovingly about his experiences, and I respected his opinions in general.  I'm baffled by the fact that when I asked three of my local high end audio shops about SUTs that they had no idea what I was talking about!  However, when I lived in Japan I learned that many users of high end rigs swear by them.