If you are serious about tubes, I would start with a tube DAC and then maybe a tube preamp. Both uses the smaller signal tubes. A tube amp uses the larger power tubes and they can take a bit more care and feeding.
That said, tubes and planar speakers can sound magical. I have owned tube electronics with some type of planar speakers since the late 1980s. I currently own Martin Logan SL3 speakers driven by an Audio Research Ref 110 tube amp and LS27 preamp.