There's no link provided, but from the AK thread you just put "Buffer Pre-amplifier" in the eBay search and you get listings of both the original 2 tube Guanzo preamp, and the one with a rectifier tube pictured here, and a few others. There's multiple sellers, some kits clearly display a transformer included, some hint there may be one, Pg recommended Pokerelectronic which has both kits listed. Looks like fun, I may dive in here.