Yes, it does, many thanks!
As I went about trying to fit the ESS DAC card into the 8-pin socket, I couldn't find any way to do this with the position of the card up against the back of the A3 chassis, so I went ahead and removed the rest of the back and bottom screws. This made it very easy to move the main PCB about 5mm to be able to plug the card into the socket. Then it was just a matter to reposition the PCB assembly back into the chassis and put all the screws back in reverse order. The volume knob made a satisfying 'click' sound when i put it back on the bolt, nice!
I tested out the card with a USB-C cable out from my MacBook Pro, works fine.
But now I'm wondering what I'm doing wrong with my iPhone. I assumed a Lightning-USBC cable would work but it doesn't. I've got the venerable Camera Connection Adapter, do I need that and a USBA-USBC cable instead?