I'm new to Step Up Transformers

When it comes to hifi hobby, matching the correct stuff together is what creates nice synergy. One might have 2 excellent sounding pieces but they might not sound great together. Exploring external SUT’s is just one of the many unique things people do to get the best performance from their vinyl setup. I own 7 SUT’s and have listened to about 15 different ones in my system. They all sound very different.  I heard some very nice ones but in the end, I settled on a SUT that uses 50’s transformers made by Thordarson. Just like everything in this hobby, there is a world of SUT’s and makers of them out there for you to try. No easy way around this once you open that door. Good luck and you’ll see that they do make a difference. 

Thanks for this very educational discussion!  

rmcfee, I’m glad I am able to share my experience with you about SUT’s. Mine journey began when I first purchased a Denon step up for my Denon cartridge. I then picked up a Ortofon and after an expensive active tube based Klimo. From there I started to realize that these things make a difference. I listened to my friends AudioNote and even though it worked great in his system, for mine it was too clean and lacking body. In his setup, it sounded great. I listened to a bunch more till I found around 7 that I liked best for me. Don’t think that because a transformer matches well in someone’s system that it will sound good in yours even if you own the same cartridge. Your system (cables, tonearm, preamp, listening room) is unique and you’ll need to hear it in your system and find the best sounding and matching SUT’s not just for your Cartridge alone, but for the system. If I were you, I would begin with searching on the web what the majority recommend what SUT’s with your cartridge. You might get a few and find them very good, but if you keeping going, eventually you’ll find the one that matches really nice with your system. 

To me, the real purpose of SUT's is to allow the use of a low output MC cartridge with a MM only phono stage. I recently replaced the McIntosh preamp in my main setup with the new Marantz AV10 processor.  It has terrific specs and very low noise, but it only has a MM phono stage, while the I have a low output MC cartridge on that turntable.  So I bought a SUT so that I could connect directly to the phono input on the Marantz.  It works just as anticipated, but I would not say it is better sounding than using the same table' and cartridge going to the MC input of the McIntosh.  

There is no better or worse here. It’s what works out in your system. I’ve heard inexpensive amps outperform expensive amps in a particular setup. So using the MC section of a very good phonostage doesn’t mean it will sound better or worse than using the MM with a SUT. If someone has great synergy with the built in MC then they are fortunate. But if the built in MC isn’t a good sonic balance with the cartridge, a person has a ton of flexibility using the MM section and exploring the many SUT’s available.  In my experience, it works out exceptionally well in getting the correct balance, - detail, dynamics, fullness, transparency, naturalness, etc.