Not OP, but I used to use a decent pair of wired, in-ear headphones with the male Lightning to female 3.5mm adaptor since I found wireless headphone quality during that time to be subpar up until the airpod pros came out. I still had a lot of issues with this configuration however as the adapter was flimsy and would break frequently, and since the DAC was now placed in the adapter itself, the audio quality was noticeably worse than in the previous 3.5mm models. But even with good bluetooth headphones, bluetooth just doesn’t have enough bandwidth to listen to music at high fidelity.