Which preamp for a pass labs?

Actually at this level these components are balance from input to output. There is no balanced to single conversion going on. Both the LS25 and the Pass X amps are meant to be run balanced but will work with a single ended connection. But that's really kind of a waste of what these components can do. If you run the LS25 single ended you're literally only running one half of the preamp.

If you're going this route go buy good XLR cables even for short runs. I agree a lot of components are single ended internally but not the ARCLS25 or Pass amps. Otherwise you'd be better served with components that are meant to be used single ended. It's part of the reason these boxes cost what they cost.

I am using ARC Ref 5se with Pass 100.5's and switch with an ARC Ref 75. I am actually having a hard time picking which I like better. When I was looking I was told, that the ARC LS25 MKll is a very good preamp and the Ref 3 just a little better. I never considered a solid state Pre amp, because I like the warm sound from the tubes. I will admit I have been an ARC fan since the SP 3.

OK- why just ARC and Pass- no other choices?

I would suggest a balanced tube preamp for a Pass and there are plenty out there.

All the "balanced" hype is pure BS.

This statement is false. To start with there is no hype. To end with, the balanced line system was devised specifically eliminate artifact from cables. If you like one cable over another in an audition, then you know what I mean by 'artifact'.

I am constantly amazed that there is any push back at all on balanced line- you'd think audiophile types would love a cable that is simultaneously inexpensive, tonally neutral, low noise and revealing, in any length. Why pay more for cables that don't bring home the bacon?

faxer-
where are you located?
Happy Listening!

I am in the 'Tubes Somewhere in the system" camp.  Pass SS power amp and a tube pre is a sonic match made in heaven.  (I run an Ayon Eris into an X150.8).  ARC, Cary, Ayon and I am sure quite a few others.  Uber-tip:  A Pre with 6H30 tubes is liquid gold.
Cables:  Go for something cheap and cheerful.