As I understand, an option: "Maximise compatibility" must help you! You can look on my screenshots, attached here. For me an iBasso DX300 is connecting smoothly to my iPhone 12 Pro with iOS 15.0.2, when that function is enabled.

Hello, @Whitigir, First of all, thank you very much for your efforts related to enhancing quality of such a perfect DAP, like iBasso DX312. And moreover you share such ideas like Amp12W freely on a forum - it's cool and worthy of respect. I am planning to implement Amp12W for myself - in...