I've owned a lot of preamps at a lot of different prices. As my ear has become more fine-tuned, it has exceeded my budget. It sounds like that might be the case with you. I would suggest you look for a solid-built used preamp whose reviews describe what you're looking for. I just traded-om my ARC Ref. 3 which was a wonderful preamp, but I'm getting out of the tube business. I purchased a Pass Labs XP-30. In the reviews I read, the new XP-32 doesn't much improve on the XP-30's sound. But that was way above your budget. Pass Labs have some single box preamps (mine is three boxes, separating power supply and each channel). I'm not sure how much clarity all those boxes buy. Pass does have single-box preamps.
I would look at what Audiogon and other used sites are selling. If you look at a known company like Audio Research, you'll have to read reviews. I bought an ARC LS22 used. It sounded wonderful and seductive at first, but then I began to hear the bloated bass and brittle treble, both of which were hidden by the voluptuous mid-range.
I think you have to do a lot of research fast when you buy used. If there is a deal out there, it will go fast. You might have a few hours to figure out if it's what you want. In my experience a preamp with the attributes you listed does not sell new for $2K.