I'm been making some progress on the Altium schematic!

Although mostly complete, there are a lot of annoying "Altium-y" things left to do that mostly revolve around footprint hunting and component selection.

Here is a higher level schematic that more-or-less resembles the initial sketch:

The design is mostly a bunch or repeated power supplies and a signal conditioned from an isolation amplifier (not that it was going to be anything else). What is making it interesting, however, it the power restriction set by the extremely limited space in the enclosure that is forced upon me by the two 1VA transformers:

I'm finding it impossible to locate a small quad-secondary transformer, which would have a higher power density compared with two lower VA dual-secondary transformers. The OPA2134 op amp (I'm using two) and ISO124 chips all demand 2k ohm loads for ideal performance, which is before any output is actually connected. This is forcing up the size of the transformers and consuming space. I'll need to invest a lot of time into both reducing the sizes of components and thinking of clever placements if I'm going to fit everything in the box (which I certainly aim to).

I think this is going to be a fun layout!