What tube pre-amps pair well with Pass amps?

Hay Atmasphere, thanks for bringing that point up.  May I respectfully ask for the names of some pre-amps that meet AES48?  As you can see, I'm on a steep learning curve and I know I have a lot of work to do, so any further guidance/direction is appreciated.

Yabe, do  6H30 tube pre-amps meet the AES48 standard, or is the tube topography considered separate from the line output?  With  impedance matching, I assume your talking to pre-amp/amp impedance?  Can you expand on what your looking for?  FYI, I may be misusing some terms.  If so, please correct me.  TIA.

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...