BAT VK51SE pre and Krell FBP-300 amp. One of the great Dan D'Agastino class A designs from before he left Krell.
While I have often paired tube preamps w/ SS power amps and believe this route often makes great sense, the pairing of amp and speakers is far more important. IMHO, the preamp choice is more independent unless you have a relatively rare impedance mismatch.
If you are dipping your toe into tubes for the first time, preamps are certainly a simpler and less costly way to do so. Tube rolling options are WAY more available (vs. rolling tube power amps) and will allow tuning to your personal taste easily and at modest cost. Cheers,
Spencer