@rauliruegas @enginedr
I have not listened to any of the SUT’s that you mentioned, but I have listened to some very good vintage SUT’s, both factory assembled and DIY assembled. None was as good as the 1931Ag, and only one was close.
We all three seem to be pretty much agreed, though, that even the best of the SUT’s is not quite a match for the best high gain phono/pre. I suspect that I could not tell the difference between the 1931Ag and a phono/pre using teflon or styrene caps for RIAA - it’s only by using vacuum and air-gap caps exclusively that I can differentiate. I suspect.