I finalized the buffer kit design, and ordered a couple prototype boards today.
This is the piece needed to turn the phono board into a full-function preamp. Or to be a standalone buffer (no gain) preamp. Now I just need to find a potentiometer to include with it. Or maybe an inexpensive one so people can build their own stepped attenuators or use their favorite pots. I have used lots of Alpha pots from Mouser and they are pretty good. I might just include that so people can use them or upgrade to something really great if they want.