Best tube preamplifier for under $15k

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.

+1 for the Vinnie Rossi
Have loved Vinnie’s work since Red a Wine Audio. He really knows what music sounds like and is able to infuse that.
My other very high recommendation is Audible Illusions.
A rare company that has specialized in only making preamps for decades. They have kept improving and have been listed in TAS at “the best at any price” forever. I happily live with mine. Ultra neutral with only one tube pre channel in single ended with an external power supply. 

I listened to a number of tube preamps in the $7K to $10K range ($15K is outside of my budget) and landed on Balanced Audio Technology (BAT).  What a fantastic design philosophy, and sonically it delivers a phenomenal soundstage with imaging that is a mile deep.  Sonically I find that everything about it is, well, just right.  The VK-33SE is $10K but you can go up from there to the VK-53SE at $15K.
They do operate with a remote, which comes in the box.  A very well made, all aluminum remote that is not cluttered but has just the right amount of function controls.  A very cool feature on the remote is a "fade mute" function.  One touch button and the volume fades away rather than a hard mute (though there is a total mute function, too).  You only realize how wonderful that feature is once you have it.  The preamp features are great, but it's the sound quality that got me.  I am surprised not to have seen others mention the BAT brand.  It's very well reviewed and regarded in this industry.