A quick update... after looking at how much work it would be to assemble even a small batch of perf-board prototypes, it seems like a better idea to go ahead and design some circuit boards and have them made at a board house. So the past few months in my spare time (which isn't much) I have been learning Eagle and attempting to design some boards. I have several designs, including the buffer and drive sections of the Pi and the TS buffer circuits that I used in the POC. After a few iterations of the Pi circuits, I realized that there are common enough features that I can design a single board to handle both the buffer and drive by either including or excluding components. This is great news, as it means I can get a batch of these and choose the function when the components are soldered on. I still have some things to add, such as the OS licensing marking and Project name, but here's the first rough schematic:

The holes on the right are for the mounting, stacking headers on the left, and JP4 is for the external input pot. The dashed line boxes are for the optional components that determine if the board is an input buffer (in which case it feeds the "Dry" bus channel through a cap) or a drive section (where diodes are added for clipping). The pot in the bottom right adjusts the Collector bias for controlling clipping or gain. If the pads look close together, I plan on mounting all of the resistors and diodes in a vertical configuration.

I'll post another update when I get some more boards routed and make an order.