I bought a lightning to 3.5mm adapter to use my sennheisers in my iPhone 12 but they sound so much better plugged straight into my old Samsung s9. I’m no expert so I don’t know how to explain the difference but sounds so much more crisp and can decipher all the different sounds on Samsung. Can I make them sound better through my iPhone?
If you wanted to make the sound quality even better, you could consider purchasing a separate DAC for higher quality. As Otherwise-Rope8961 correctly said, different devices have different Digital to Analogue chips, which do affect sound conversion. I’ve tried plugging in my Hifiman Sundara directly into my old Samsung S7, and I got a sound output only in the right ear, weirdly. Probably dust and stuff in the aux in connection.
You might have a low quality lightning to 3.5mm adapter though, and Apple can be quite pesky with sound and outputs. My headphones have just randomly stopped playing when I’ve got them connected to my iPhone 14 even with a DAC.