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
Scothurwitz

Thanks for the reply.  I'm currently running Prima Luna Dialogue pre-amp and 2 HP amps as mono blocks, which I intend to keep (read tube rolling fun) in a 430 square foot room.  The PS audio pre-amp has been on the screen, as I have their DMP and DAC.  With this matchup, do you think the Pass Labs XA 30.8 has sufficient power for the Sopra 2's?  I've always been intrigued by Class A amps and its on my bucket list. 

One last thing, do class A's handle sub-woofers? 
The most helpful information you could provide would be what sound qualities you value and/or would like to improve upon.  Without that this is really just a shot in the dark. 
SOIX, you are absolutely correct.  I've just relocated and am in the process of addressing my new room's acoustics.  Treatments are on order and until I get the set up I won't really be able to tell where I'm at.  Until then, I'm just searching for possible ideas.  Since my current system is all tubes, I'd like to explore SS with a little more slam for complex and/or dynamic music.  

Thanks for your reply.
I have a Pass XA30.8 paired with a VAC Renaissance MK5 preamp.  Works very well together musically bolstered by design compatibility in impedance, gain, and both having fully differentially balanced circuits.  Drop a pair of NOS 6922 into the VAC and you get the quietness of a Class A SS amp paired with the tubey goodness of the VAC.  A perfect pairing in particular with speakers around 8 ohms and 90dB sensitivity in my experience.