Where do you put the adapter when you're listening through some other 3.5mm source though? That's what I'm most worried about, as someone who will be buying his first headphone jack free iPhone.
Basically the only time I used headphones in my normal life is at work. The only time I stop using them with my phone was when I would plug them into my desktop for some reason. That was usually temporary so I just left the adapter next to my phone and it wasn't an issue.
These days are use AirPods and just switch them between computers so I don't have to worry about the adapter anymore.
But the adapters are only $10 so it's not that hard to have a spare or two.
