Even in the relatively small world of high end audio there are of course different schools of engineers. Two like-minded engineers were (both are recently deceased) Roger Modjeski of Music Reference (and RAM Tube Works) and Tim de Paravicini of EAR-Yoshino, both experts in the field of tube amplification circuitry and the design and build of transformers.
I have found the EAR-Yoshino 868 pre-amp to be a superb partner with any of Modjeski's power amps (the RM-9, RM-10, and RM-200, all of which I own in Mk.2 form). The EAR 868 affords both single-ended and true AES48-compliant balanced outputs (via Paravicini's own transformers), so can be mated with both the single-ended input RM-9 and RM-10 amps and the balanced-input only RM-200. Unlike almost all other tube amplifier makers, Modjeski hand-wound his own transformers.