I have made a number of incremental changes to the design, and things are starting to be ready to start thinking of ordering a rev 1 board. However for this revision, I have removed support for picking one of either OPA549 or 548. The two chips have different pinouts, and adding components for both on the board (with the intent of only populating one) used a lot of space, plus limited how close I could place some components (such as bybass capacitors, which were supposed to be as close to the chip as possible).

I have thus removed the 549 package. In future revisions I may re-add it (possibly on it's own board so that I don't need to make compromises in the design.

As an overall status update, I am more or less happy with how things are looking now. I am going to be discussing the overall design with a friend who is also making one; if things look good there, I will be placing an order for components. The next step would be to prototype the thing on a breadboard (only low current output, of course), and, finally to order the boards. As timelines go, I hope to have the board order placed by the end of the month, and so will hopefully be doing the component order within a week. (Here's to the ability to stick to non-binding schedules!)

An updated schematic is below.

Cheers