At the Burning Amp Festival in 2017 Nelson presented a pre-amp using the Korg Nutube dual triode. The latest revision of the circuit available is now available complete with Fairchild JFETs and all directly supplied by Nelson Pass. 

Purchase just what you need based on what you have in your stash or get everything you need in a complete kit.  The complete build guide helps DIYers just getting a start to complete an exceptional pre-amplifier in a few afternoons.