Best Used Tube Based Preamp $2k Or Under?

You might find an LTA MZ3 for close the $2K, for sure you can find the MZ2 at that price. And either will double as one of the best headphone amps you'll ever hear. 

One the worst regrets I have is  not listening to more seasoned Audiophiles earlier. I purchased a Conrad Johnson ls 17 last year . It has 1 year of smiles .The only other brand I would consider  is ARC LS 25 or LS 26 . Both brand are built like a tank . If you want to sell or trade up no problem in finding a buyer . Buy once and cry once .

A lot of my favorite ones were 6sn7 preamps. I prefer four 6sn7 preamps, 2 per channel so I can blend 2 different brands sometimes if I need to use as tone control. Ken Rads and RCA’s work well together plus many others or load it with four of the same tube.

I really enjoyed the Don Sachs with the Kootenay. Spratek is very nice. I really liked the Conrad Johnson but ones in the $2000 range may be a little fuzzy and slow great with blues and jazz but can struggle with other complex music. Audible Illusionn or Bruce Moore are nice but can be hard on tubes, I had a VTL 5.5 long ago and really in joyed it. Cary or Dennis Had are very good amps.  I had an ugly black box Don Allen preamp that was very special 20 years ago I wish I would have never sold. There are some nice ones out there in your price range.

The rogue rh-5 headphone amp/preamp with remote is hard to beat only 2 tubes, balanced and single ended and and very musical as well as dynamic highly recommended