$20k(ish) tube preamps

You should also consider the Nagra Classic in that price range.

No support for the VAC Master? i'm surprised as it's on my short list, tied to my Gryphon Antilleon EVO stereo. Not trying to hijack the thread, but any thoughts on the Master?

I've been running an Audio Research Ref 6SE for a little over a year and I couldn't be happier.

What are you replacing?

You won't do better than an Allnic L9000.

https://soundstageultra.com/index.php/features-menu/opinion-menu/106-uncategorized/1031-allnic-audio-l-9000-otl-ocl-preamplifier

No support for the VAC Master? i'm surprised as it's on my short list, tied to my Gryphon Antilleon EVO stereo. Not trying to hijack the thread, but any thoughts on the Master?

I love mine but the Master retails at 28K (possibly more now?), and 40K with phono stage. A used one can come in under 20 but I don't know if that meets OP's criteria. It's definitely a great match for powerful Solid State amps and high power tube amps. Has the classic "romantic" tube sound, while also being extremely articulate and refined. 

I also like my ARC Ref 6 a lot, and the 6SE should be even better.