What tube pre-amps pair well with Pass amps?

I am using the Pass Labs XA-60.8 amps with the Pass Labs XP-22 preamp in balanced mode and I can only say the musical presentation is outstanding in every way. It is very musical and not in the least anemic or lifeless. I have not heard any other Pass Labs preamps, but what I am hearing now is the best I have ever had in my system. 

Pass Labs whether due to technological or marketing reasons promotes their “super symmetry” as a selling point. This might be best used in balanced mode. Some of the Pass Labs amps have a somewhat low input impedance.  If wanting to use tubes, I suggest considering the Atmasphere and Sonic Frontiers pres.

@unsound If you're curious, here's an article where Nelson explains what the term actually means... https://www.passdiy.com/project/articles/super-symmetric-amplification

@cal3713 , Yes, thanks. It’s been a while since last read. ...Hence, my suggestions.

I stated earlier in this thread how great my system sounds with a Pass Lab preamp and Pass Lab amps. I have now heard the Aric Motherlode II in my system and it sounds amazing! If you want a tube preamp you should definitely talk to Aric. I ordered one today!

+1 @jake18aa
I felt the same when I matched up my Pass XA25 with an Aric Audio preamp! This combination makes a wonderfully musical, holographic, and natural presentation of the music that I find extremely satisfying!