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
A few iterations back, I had a pair of Sopra II's, the Pass XA60.8's, and Aric Audio's Motherlode preamp...it sounded fantastic! Fast forward to today, and the only piece of gear still in the system is The Motherlode. Call Aric and you will not be disappointed. 
Post removed 
+1 laaudionut. I own the Aric Audio Special preamp. Using it now with a BEL 1001 MK5. Plan on getting a Pass XA25 in the future. 
I'll just note that the aric audio preamps are also 6sn7 based. I'd love to hear one, as every review is very positive (and I agree with many of his well-advertised design options).
+2 for the Aric Audio preamps! @laaudionut, @mesch 

Since we are on the topic of the Pass Labs XA25, I am now running a souped up Aric Audio Special 6SN7 preamp with mine, replacing the already excellent Backert Labs Rhumba preamp, which I used for 3 years.  This was Aric’s own preamp that he used to voice his latest Motherlode II preamp, and it retains most of the Motherlode’s sonic characteristics.  It’s an amazing match with my XA25.