What Tube Preamplifier Under $1800 to Choose?

I moved from the Quicksilver preamp to a design based directly on the DeHavilland Ultraverve III, which you can get used, here: https://www.usaudiomart.com/details/650263291-dehavilland-ultraverve-iii/

The Quicksilver was good but still to dry, clean, cool in tone. The 6SN7 tube gave me more that I liked – dimensionality, space, warmer tonality. That is how I’d focus my looking if I were you. Keep in mind how many tubes a preamp requires. The nice thing about the deHavilland is that it only has one 6SN7 tube.

I’ve heard great things about the Cary and Rogue, and many also like Aric’s preamps, though they might be too expensive. There is also Erhard.

Modwright is a solid brand:

https://www.usaudiomart.com/details/650310634-modwright-swl-90-tube-linestage/ and

 https://www.usaudiomart.com/details/650304848-modwright-swl90-ae/

The Herron is also respected: https://www.usaudiomart.com/details/650268318-herron-vtsp-1/

Good luck with your search. There are other brands of course – I've mentioned above what my research kept revealing as among the most well respected brands and makers.

https://www.usaudiomart.com/details/650304848-modwright-swl90-ae/

The Galion Audio TS P75 is just a tiny bit more than what you’re looking to spend but you may want to check it out. My system for the past 20 years has been an Emotive Audio Epifania tube preamp and the Vita monoblocks. The preamp was $17k when it was released and it’s fantastic. With that said, I recently purchased the Galion Discovery amps and was blown away by how great they sound for money. They are voiced with a V shape frequency response: pronounced bass and highs and a recessed midrange. The TS P75 is designed to fill in the midrange with some warmth and tonal density, and smooth out the top end. I bought one but it was delivered right before I left for vacation so I only have a few hours  of listening but I can say that it has the type of sound you are seeking.

Rogue RP-1 is excellent. Responds ro tube rolling so you can tailor the sound the way you want. I really enjoy my time with the RP-1 and never thought of it as a bottleneck 

I would buy that dehavilland III at the price listed all day!  I bought one new from Kara about 5 years ago.  It's dead quiet to a Pass XA.25 and La Scalas, which was a surprise given that tubes can be noisy and La Scalas are not forgiving with their efficiency.