Which SUT to match Koetsu Rosewood Standard in my system?

Thanks, @cleeds. So how does that cash out for my situation? Should I then be aiming for something around a 1:10 step up for a 0.3-0.4mv cartridge?

I don’t think that Audio Note publishes that spec. I could be mistaken, but here’s the manual: https://www.audionote.co.uk/_files/ugd/89c24f_e3f648926d024a13b9846ae2269296f9.pdf. See page 9. Is there a way to test for that? Or calculate it from the specs they do provide? Based on specs for some of their comparable standalone phono stages, it appears that it could be anywhere from about 36 db to 56 db.

As for the cartridge, output voltage is 0.4mv. Koetsu is also a bit stingy with specs, and doesn’t publish internal impedance (so far as I can tell). But other sources say it’s 5 Ohms. 

Thanks for all of the advice so far. I’ll reach out to Audio Note to see if they’ll provide that info.

One other piece of potentially relevant info: I do have the Hegel V10. Would it be useful to play around with gain and capacitance settings on that first, and see what works best? I just wasn’t sure if the combination that might sound best on the Hegel would necessarily translate to what would sound best on an SUT. 

@lewm on the question you asked: 

Other important variables and unknowns include linestage gain and amplifier input sensitivity and speaker efficiency. 

The Audio Note manual says that line level input efficiency is 300mv, and line level input impedance is 100 Ohm. I’ll report back on gain.

As for speaker efficiency, it’s 99 dB. Thanks. 

I do like the Hegel overall, but it’s almost too “clean” and precise, if that makes sense. It does something to the signal that, at least to my ears, takes away some of the warmth and magic of the 6L6s in the Soro. I suppose I could be imagining that—it’s always so hard to separate physics from psychology in this endeavor.

But the dealer who sold me the amp said that Audio Note designed its phono stage to be used with SUTs, and he thinks it really shines best with a SUT rather than an active phono stage. He actually steered me away from Audio Note SUTs for now, as he thinks there are better bargains to be had at my budget than AN’s mid-tier offerings. So I don’t think that he’s just trying to sell me another Audio Note component. 

@rauliruegas You do make a good point, raising the age-old debate of accurate reproduction vs. subjective pleasure. In my experience, having listened to some of the most accurate systems on earth, reproducing exactly what’s in the grooves doesn’t always equal subjective enjoyment—which for me is the sound of live performance.

That said, you’re quite right that the Hegel is a great unit. That’s why I bought it in the first place, after all. Fremmer’s rave review, among many others, certainly sold me on the Hegel.

It’s quite possible that the Hegel sounds “clinical” to me only in direct contrast to the Audio Note’s built-in tube phono stage. Also, I’ve only tried the Hegel with my 540ML (which is ”cooler” and more clinical than the Koetsu, at least to my ears) and only through the Audio Note’s line stage. It may be that the Koetsu + Hegel + AN phono stage combination would work quite well.

And as @elliottbnewcombjr mentions, the Hegel gives nice flexibility with independence gain and impedance control. Perhaps I can find a combination that gives me what I’m looking for, and can hold off on the SUT search. I think the wise thing would be to start there and see what I learn.

I still welcome any thoughts on the SUT in the meantime. I’m a tinkerer, and I know I’ll want to give one a try sooner or later.

Thanks to all so far for the quite helpful advice. In my short time on the forum, I can already see that this is a welcoming, productive, valuable community. 

Also, @elliottbnewcombjr thank you very much for this clarification:

Your Amp's phono specification: phono input sensitivity 3.0mv. Not Ideal, not preferred: That is the MINIMUM signal strength it needs IN to boost the signal up to line level. These amp's phono inputs also have MAXIMUM _____ mv, (before overload occurs) 

I had no idea that’s what that specification indicates. You learn something (or several things) new every day!

Thanks for all the recommendations and advice. Now to see who out here on the west coast might have some of these options to audition.