Best 3 tube preamps under $18000?

VAS II, about $5000. Classic design, top of the line materials. Yes, it cannot beat the ARC unit, but hey, it sounds great and is a super value.

The ARC Ref-5 is definitely a nice pre and I would only recommend it if you can live with the fact that Audio Research will come out with a Ref 6 in about 3 months and that your ARC 5 will not be upgradable.

I would seriously have to stretch a couple of grand for the BAT REX or get the VK52se which may not be the best under 18k but it is upgradeable to the rex which is one of the if not the best pre-amps out there at any price.

There are great brands, like the Forsell Fetcode and the Millennia...they are fantastic.

Let's throw a couple more on the pile:

CAT SL-1 Ultimate
Allnic L-4000
Atma-sphere MP-1 (yeah, I know it's been mentioned, but it deserves to be nominated again)