YBA Passion 1000 mono, which preamp to match?

Anybody with an exprience with the YBA Passion 1000 monos?
A great matching preamp (ss or tube).
Any suggestion or recommendation is welcome.
Thank you.
My friend had the Passion preamp with the Passion Stereo amp.
He's moved on to the YBA Signature monoblocs. He's still happy with the Passion preamp.
He's using the top YBA CD player, with Nottingham turntable & Kharma speakers.
why mess with a great thing? If you've got the Passion, why not stay with it? --PASSION PREAMP! I own the Passion Integre. I've been a Yba fan from way back. Yba stands with the giants. Always has. Don't hear enough about them, for some reason. peace, warren
Unusually perhaps, the CAT Ultimate (or Sig III) provides an excellent interface b/ween source & Passion mono.
Pls note that my experience is with the Signature+ passion combo; however, people who have upgraded fm sig to ultimate seem to prefer the latter.