What tube pre-amps pair well with Pass amps?

I have to disagree with Atmasphere on two points:
1. I have a fully balanced Pass Labs XA60.5. The cable does make a difference.
2. I have two high quality Cary preamps. Cary SLP-98P Formula 1 mod, which is single ended. Cary SLP-05, which is fully balanced, but not upgraded. The single ended preamp sounds better with the Pass than the balanced in my case. That is why I am upgrading the SLP-05, for better SQ.
The bottom line is that preamp quality is more important than using the amp in the balanced mode.
Btw, make sure that if you use the Pass Labs in single ended mode, to insert the shorting jumpers, so that the unused half does not introduce noise.

One caveat to my points.
My preamps are very close to the Pass amps; so the interconnects are short. With a longer interconnect run, the balanced connections may possibly be superior.

@billtro Ama-sphere (unsurprisingly) makes preamps that conform. I presume that Pass does as well. Unsure unfortunately about other brands, perhaps some others will know of some options...

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.

@cakids   +1 !

The bottom line is that preamp quality is more important than using the amp in the balanced mode.