Best tube preamplifier for under $15k

Linear Tube Audio MicroZotl 

Since no one else has mentioned them, VTL makes some great sounding preamps under your budget. You don’t say if you want a built in phono stage, but they offer with or without. 

Lots of MicroZOTL fans - very interesting. 

I should add that I require remote. That probably takes half the suggestions off the table.

To those making fun of the price range, I just wanted to be all-inclusive and the ARC Ref 6 lists around that much which most consider a standard-setting piece. I actually own a Music First Baby Reference TVC that doesn't cost half that and sounds amazing - but it doesn't work with a particular amp in my stable. Hence the need to acquire another preamp.

VTL 7.5III hybrid tube preamp. It's a linestage with one pair of 12au7's in the gain stage. Fantastic sounding pre.

With a 15k budget, I would seriously consider the Vinnie Rossi L2 Signature Preamplifier.  Perhaps a demo/used can be had for less than your budget.