Last year, Philips launched its Fidelio M2L headphones that plugged straight into an iPhone's Lightning port. Now, it has a noise-cancelling version, which draws power from the port and negates the need for batteries.
The Fidelio NC1L headphones use the same 24-bit digital-to-analogue converter as their stablemate, instead of the one on board the phone. That means the digital-to-analogue conversion that usually happens inside your device can instead be processed inside the headphones. And that eliminates the analogue audio signal having to be sent through a long headphone cable during which it can be subjected to interference and degradation along the way.
But they also offer active noise cancellation, using four microphones to monitor external buzz before inverting it to cancel out background sound. That's nothing new, but usually noise-cancelling headphone require batteries to keep their circuitry running. Because the Lightning port can also provide power, though, these headphones don't need their own source of juice -- instead, they will.. well, they will run your iPhone's battery down instead.
They're certainly lovely headphones, and the fact that the audio is converted to analogue at your ears means that their sound is clean and clear. But then, at $US300 for a pair when they go on sale, it better be.