Contact Bob latino, I'm pretty sure he can build you one. If it's really just an itch, amazon has cheapish tube buffers in their chifi electronics section.
Buffer amp no gain
I would like to put a buffer stage between volume control and power amp to ensure impedance matching. I like the look of the First Watt B1 but don’t need the volume controls.
My volume control is a passive ladder type with expensive resistors, silver wired etc
So my question is, can I buy a buffer with phono inputs and outputs but no volume pots. Either valve or solid state is OK.