"If you’re taking this opportunity to really make an investment in the best you can get, then go with the Audeze EL-8 Titanium Closed-Back headphones. These are top of the line planar magnetic headphones and has been taking full advantage of the Lightning port on the iPhone for a while now. Thankfully the cable is removable and you can swap it out for a standard 3.5mm audio cable. This way you can still use them with your computer or audio equipment whenever you need to."
"But there is one key benefit to using their Lightning cable instead. Audeze calls it the “CIPHER” cable, and it has many of the key audio components required to drive high quality headphones built right into it. Where you would normally find a control module with a mic and playback controls, the CIPHER cable has an inline digital-to-analog converter, a headphones amplifier, and of course a Siri-compatible mic for calls. Your iPhone has more than enough juice to power these, and being plugged into the Lightning port gives the EL-8s access to all of it. Of course, these are high end headphones. Even without the iOS compatibility they wouldn’t be cheap. But if you’re getting tired of carrying large DACs and headphone amps, these are a sleek all in one option."