Buy an Audio Research SP10 MkII or an SP11 MkII ?

For the sound you're describing, Wendell is correct, the SP-10 is what you want--it has a very good phono stage too. The 11 is a hybrid design, and sounds more neutral but definitely more like solid state than tubes. If you want to spend more, a Jadis JP80MC, particularly an earlier model, would also fill the bill (I assume you want a phono stage along with the line stage in your preamp).

My still-good friend and I were in the high-end-audio business in the early- to mid-'80s, and he knew LOTS more than I about these things. Here's what he said:

"If he’s looking for a preamp with a vacuum-tube signature, then the SP-10 is his best bet. That said, the actual sound quality’s very much tube-dependent and as I recall, they require replacement at fairly short intervals. (As an aside, the low-level tubes came from ARC with rubber damping rings installed, an idea that the SP-10’s designer, Jack whatever-his-name-is, “borrowed” from me after a long discussion we had about various methods to address the microphonic qualities of tubes when he called TJA late one afternoon to buy some capacitors because ARC’s usual supplier had run out…)."

Based on all comments so far, the SP-10 is definitely your best choice. Also, you may be in serious pursuit of NOS or premium current-production tubes if you buy one. Looking here http://www.arcdb.ws/SP10/SP10.html , the -10's fono section has SEVENTY-TWO dB of gain, plenty enough for that Rosewood Signature.
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I agree on the Jadis JP80MC. Without a doubt the finest tube preamp I have ever heard but a whole lot more money than the SP10. I would love to own one but it is more than I can afford.

Wendell

The SP11 was too cool, clinical if you will, for me. I've been using my SP10II for over 20 years and nothing else has tempted me. Tubes are an issue, you need quiet and rugged tubes.

I have owned both and have kept my SP10. it will never leave me as I have not found anything that comes close for my personal taste. When I first received my SP11 many years ago, I fell in love with it. But after a while, there was something about it. I would like to say it was solid state like but I want to avoid that argument. To me, it didnt seem as "real". I ended up selling it and guess what. I didnt even miss it. When I first received my SP10, it had Sovtek tubes in it. I then put in Siemens E188CC and it blew me away. I have owned many tube pieces, some are less sensitive to tube choice. But I always call the SP10 a tube microscope. Changes in tubes make a big difference. If you find the right combination for your tastes, this unit will shine. I love my SP10 and unless financial circumstances dictate otherwise, it will never leave me. I managed to stockpile 2 complete sets of siemens tubes for future use. I have owned an incredible amount of systems and have finally identified pieces that I wont sell unless I have too. With these units, I have pretty much stopped chasing the audio upgrade because I have found units that allow me to focus more on listening than chasing audio perfection. This doesnt mean I have others I dont want to sell :)) I guess you will find many different opinions and there are some reportly good offerings out there from Manley, BAT and others. But I figure I wont do much better spending $2500 on an SP10 compared to $7000 on a Manley. If its worth it to you and you have the bucks, go for it. I wouldnt object to owning a Manley Steelhead. If nothing else but for the support and postings I see from EveAnna backing their products. That is also important to me. But its not in my budget range and these days, i would rather spend the money on picking up music or comfortable chair for listening or more tubes for my beloved SP10. Good luck in your search.