[jaywalk]

Shure SE215 and the default tip it comes with. I can only speculate on why the IEM is better, but I suspect it comes down to the tip material creating a better, more substantial seal. The outer shell is also physically larger, and that may also play a role in keeping more sound out.

[hackerlight]

I wonder if we can replace the tip on the Airpods Pro to create and IEM like seal. I suppose that should be the best of both worlds? But the outer shell would still be smaller so maybe not.