I think (TBC) that we need a passive adapter, meaning without DAC built in. The Apple one is including a DAC. Maybe Steve can clarify this ?
I will have the same issue in a few weeks when my Theatre will be delivered, and I am based outside UK too (BTW Steve, why are you not shipping overseas anymore ??).
I am considering this one that seems to work in analog: https://www.amazon.fr/gp/product/B076X8W2QR/ref=ox_sc_act_title_1?smid=A3EAOHXRU1PEZY&psc=1