Things bode well. My, er, my friend's, values are different than yours, but I'm getting voltages in the 1v-2v range on the SCK, WS and SDIN pins, and those voltages change depending on whether the empeg is paused or playing. The SDIN pin fluctuates on voltage as it's playing and is pretty steady when it's paused. It's a low voltage in the range of 1.4v when paused, and closer to 2v when it's playing. I think that tells me the empeg might be fine, and all my, er, my friend's, problems are entirely on the bluetooth chip.

Phew.

OK, now this raises the question of our design. What can we do to prevent other people from making the same mistake and frying their stuff too?

Or maybe we won't need to worry with our new pinout scheme. I wonder if the frying happened only because I, er, my friend, was using the old scheme with the RX/TX wires being used for the SCK and WS pins. Maybe with the new scheme this won't be a danger (maybe we'll luck out)?

The new scheme will have IISC on the originally unused purple wire, so there's no danger there for that one. IISW and IISD1 will be on Tuner Level and Tuner Signal. I wonder if that might fry the tuner but not the empeg if they did that? Dunno.

Anyway, live and learn, right?