Best tube preamplifier for under $15k

The Cary SLP-05 is an excellent preamp.The Supratek Cabernet [and probably Sauvignon] are better though.And cost less .They are made to order however so you have to wait for them to be built.

@Keithr, Nice of you to assume what equipment I’ve owned and compared to..  I’ve been doing audio for over 50 years and spent enough to know you don’t need to spend as much as you think..
some of my previous preamps, BAT VK5i, Blue Circle BC3, Django TVC Passive (still using), Bel Canto DAC 3.5 VBS, DeHavilland, Cary audio, a couple of ones I built via AES, and others I don’t  remember..  The Freya equals or bests most of them..  While it’s not the “ultimate” preamp out there.. It’s quite good and will compete with units costing much more.. But many audiophiles need to spend more to think they’re better...

@Three_easy_Payments. 
“I'm not sure why you'd need to spend $900 on a Freya when you have a perfectly acceptable iPhone and earbuds that sound just fine. ”
I don’t want to imitate your sound system...  I like mine just fine..  but thanks.. 

@tinear123  How did you like the Pass X-22 overall..  I’m considering the XP12 mainly because of the volume control which is used on the XS pre.  I’m happy with what I have and the flexibility... but i want to TRY a Pass preamp with my pass amp.. I haven’t heard a complete pass combo and I’m curious to give it a try...  sighs..  I’ve been Tubes all my life, but this Pass amp is making me want to try a SS pre.. thanks.

I haven't tried enough to declare any best, but I will concur with those above who vote for the Don Sach's 6sn7 pre, I love mine. 

I'm also surprised more people who are into tube-based pres aren't mentioning DHT designs.  They are challenging to build without noise/microphony, but the above designs by Thomas Mayer and Vinnie Rossi provide two well-reviewed examples.  Allnic provides some others that I'd love to hear.  Out of curiosity (started by 6 moons and my ownership of Coincident speakers) and the fervent online following of DHT designs I'm having Radu Tarta build me a custom two-chassis unit based on the high gain EML 20AM tube.  Hopefully in a couple months I'll find out that the DHT adherents are correct.