No, I tried that very early on. And the 8-digit code from the HU is random and changes regularly.

The use of a PIN precludes the use of SSP. So since SSP isn't working, I'll try the even older PIN method next, perhaps later today.

But thanks for everything to this point -- very very happy to see this project going well at your end!

Subaru's choices of head units over the years have had consistent reputations for difficult BT pairing, often requiring bizarre workarounds. Probably something like that is hitting me here.

I'll exhaust the possibilities here first, and then perhaps hunt for a BT 4.x module to try. There don't seem to be many (any?) around that do audio, but some must exist.

There's even a (paid) Android app that claims to support having the handset pretend to be pretty much anything over bluetooth, with full packet tracing. But no way to know if the claims are true without up-front payment, so I'm holding off on that for now.

Cheers