Is a SUT needed?

@handymann 

Glad to hear my suggestion helped with your problem. I assume you just replaced the V1 and V2 position tubes left and right. Those are most sensitive to noise issues.

jperry:  I replaced all four

Is an SUT needed? No but IMO (only) I find an SUT into a MM stage gives me superior results.Better dynamics more detail and a more natural presentation. I've tried many SUT's and have found the Kondo SFz step-up the best until recently.  I have recently tried tbe SA Labs SUT from Russia to now have outperformed my beloved Kondo unit, and at a less expensive alternative. 

sksos1:
Once I replaced my "new" tubes from my upgrade from a standard Rhea to a Signature Rhea, with  very low noise matched tubes, my noise floor is as quiet as a tubed preamp can be-almost.  I chose the the RCA quad matched 12AX7's from Andy, at Glenn Buckley's from Aesthetix   suggestion.  I would have thought the upgrade would have provided these, but it did not.  I have plenty of gain, as I set my input to "62."  any higher and I get over modulation.  The cost was around $300.  I could have spent more for even better tubes, but you have to place a limit somewhere.  I may upgrade my tubes from here-hard to say at this point.  No matter how much one invests, there's always something better.  I think I'm looking for the perfect system and on my budget, it just ain't gonna happen.  I'm considering different cartridges, as well as more room treatment.  Don't misunderstand-my sound is absolutely great, but there's always something better.  I'm pleased with all my hardware.  Looking for that unicorn.

@handymann ,

IME having owned a Rhea, it will be hard for you to improve on the RCA tubes, you will get different flavors, but not tubes that are more quiet.