iPhone XS max connecting to a DAC without audio

Dear Sir/Madam

I have an iPhone XS Max with the latest IOS and a subscription to Apple Music. Recently, I bought a FiiO Q3 DAC and hoped to listen to high-res Apple music, but there was no audio from the speakers. It was fine when I connected my XS Max to the wired airpods via the Apple-provided original small DAC dongle. But not to the FiiO.

My wife's iPhone 15 Pro Max, when connected to the FiiO Q3 DAC, was working fine too.

I've made several attempts to resolve this issue with my XS Max. I've tried changing lightning cables, rebooting the phone, and more, but unfortunately, the problem persists.

Please provide some guidance on how to resolve this.

Thank you in advance.

Regards

James Lee