What tube pre-amps pair well with Pass amps?


Does anyone have experience with this?  I'm running Focal Sopra No. 2s and I understand the Focal's pair nicely with Pass amps.  Any tube pre-amps you'd recommend for consideration? I like the classical rock, but am gravitating more to jazz, classical and vocals. I just want to try something new.  Thanks.
billtro
I am happy with my Audio Research Ref 6 pre and Pass Labs XA 60.8.  Can buy the Ref 6 used.
The LSA website recommends speaker sensitivity as:

Critical listening environments: 105db sensitivity and above

Smaller rooms / lower volume levels / non-critical listening: 97db sensitivity and above.

Aren't those levels speaking to horn speakers? 

KR is a Czech company which helps keep the prices down a bit compared to Germany. They are best knows as a premium manufacturer of tubes and their Kronzilla power amps.  

I sell a lot of their tubes.  Quality is extremely high though as odd as it sounds, the KR amp does really well with EML 45s.  KR tubes are best when the current can be increased when biased which doesn't happen in a preamp.  

PM me if you want to discuss pricing.