Best Used Tube Based Preamp $2k Or Under?

vtl nice but the company treats dealers very poorly.  Lousy customer service.

Look for a deal on the Rogue Audio RH 5, headphone amp line stage.  Adjustable line stage gain settings, balanced connections, smaller chassis.  Super clean and powerfully dynamic sound.  Beats the sound of the RP1; RP 5 and RP 7.  Second choice would be the RP 5.  

IMHO: I've never heard a Schiit preamp that competes with the most of the options suggested to you. I'd skip Schiit for a tube preamp.

Here is an Audio Note M2 for $2750 no connection to the buyer just an AN fan here.

https://www.usaudiomart.com/details/650185472-audionote-m2-preamplifier-balanced/

decooney,

I have had a DS1, D2, and his latest preamp, the Raven, but needed to part with Don's 300b monos so I sold the Raven in a combo deal.  Each preamp version has improved SQ, but I also had a stock Tube4Hifi SP-14 at the same time in my bedroom system and it was stellar performer, purchased used for $1100.  With Roy Mottram's upgrades, I'd guess the new V23-K1 is quite close in performance to the DS2 and I would have bought it but for the used DS2 I found for sale.  I was looking at the Supratek preamps but as far I could tell, they are all two-box units that would not fit in my rack. 

The OP has gotten some excellent recommendations to guide his purchasing decisions.  This forum is a wonderful source of information.