Preamp for First Watt F3??

Looking for good recommendations for a preamp for the First Watt F3. It doesn't have to be tubes but I have usually been using tube equipment in the past. I'll be driving Zu Definition II's and looking for new/used under $4000 that is a good match for the amp. My source has ~2v output. I appreciate the recommendations!
Easy answer: the FirstWatt B1 - difficult to match Pass' design with his own amps.
Nobody has experience with the F3???
I use it with Modwright 9SE. Superb since upgraging to tube
rectifier. That is with 99db horns - just super - if now I could have better software to play!