Yeah - I’ve also been debating one of the SP14 kits and building it myself. It seems that nearly ALL of the Preamps that many rave about DO seem to be tube types, and for a single-ended design, the SP14 gets strong reviews from a few whose opinions I trust.
I suppose that a YGGY would be a good "stepping stone" (particularly if I can dig-up a used one at a good price) to explore this option as it allows operation with and without the tubes and with a "Pure Passive" mode to boot.
Units incorporating Truly Balanced Circuits (those with more than simple transformer-coupled I/O) to drive Input / Outputs with Tubes seem to be largely beyond my price range.
I suppose that a YGGY would be a good "stepping stone" (particularly if I can dig-up a used one at a good price) to explore this option as it allows operation with and without the tubes and with a "Pure Passive" mode to boot.
Units incorporating Truly Balanced Circuits (those with more than simple transformer-coupled I/O) to drive Input / Outputs with Tubes seem to be largely beyond my price range.