Best tube preamplifier for under $15k

I'm about to pull the trigger on the LTA z40 intrgrated amp.  Coming from SS or D class, I'm told I will be blown away. 

Lots of things come and go in my system but the Don Sachs 2,pre amp stays for less that 3k it will compete way beyond its price point in the 7k to 10k category 

EAR 912

I came from a ARC Ref 1 and the EAR is a better sounding unit in my system, to my ears. 
A stunningly good piece of gear. Tone, texture, soundstage and PRaT are spot on. I have it driving an Einstein The Power Amp. Great combination. 
I listen to Jazz, Rock, Classical, Pop, Bluegrass, Ambient...

I'm envious @ewert. I have to get by with the 912's little brother, the 868L. Good enough for my modest system. ;-)

Lots of MicroZOTL fans - very interesting.

They're the current flavor of the month.