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One of the advantages of Apple's Lightning port is that it's bidirectional, meaning that it can be used for charging its host device or have the host device power an accessory connected to it. Until now most of the charging has been one-way, with iPhones, iPods and iPads receiving energy not giving it.

That's soon about to change as last year Apple quietly added a spec for Lightning headphones to its Made for iPhone/iPad/iPod (MFi) Program last year and a few headphone makers -- Philips and Harman JBL -- get set to release new models that connect directly to the Lightning port on your device rather than the headphone jack.

Philips

What are the benefits? Well, not only are you getting a direct digital connection, but the headphones can draw juice from your device to power components in the headphone, which could include an internal DAC (digital to analog converter) and amplifier that bypass the internal DAC of the iPhone and/or active noise-cancellation circuitry.

In the future, headphones with health-related sensors could potentially get their juice via the Lightning port, but presently we're seeing features such as heart-rate monitors, integrated into wireless Bluetooth headphone rather than wired models.

Enlarge Image David Carnoy/CNET

Philips' on-ear Fidelio M2L (around $300, spring) has a built-in DAC and amplifier and can play high resolution 24-bit audio, while its Fidelio NC1L, another on-ear model announced at CES last week, adds active noise cancellation. It's due to hit stores in April for $299.

As I write this article, I'm listening to a standard Fidelio NC1 , which I like a lot, though it, too, is pricey at $300. (The standard version is due to be available a little earlier -- in late February or March).

I had a quick test run with the M2L in Las Vegas and can't say I was blown away listening to a few high-res audio tracks. It sounded good but it didn't sound any cleaner or more dynamic than the NC1 and actually was in need of a slight volume boost. To be clear, it was an early unit and the Philips reps said there was still quite a bit of tuning and tweaking to be done before final units shipped.

I also played around with JBL's Reflect Aware, which is more modestly priced ($149, spring) and has a sports slant. It, too, includes noise cancellation and has no internal battery. JBL will sell both Lightning (for iOS devices) and Micro-USB (for Android/Windows) versions of the headphones.

Enlarge Image David Carnoy/CNET

When it ships, the Reflect Aware will come with a free companion app that allows you to adjust the level of noise cancelling. As a safety measure while running, I was showed how you can turn noise-cancelling off in one ear, allowing you to hear traffic better through that ear.

If you're wondering just how much power these headphones draw from your phone, it's unclear, but both Philips and JBL say they don't require much power and shouldn't have a major impact on your device's battery life.

Of course, the big drawback to these types of Lightning headphones is that you can't use them with non-iOS devices. But if you're someone who doesn't like having to charge your noise-canceling headphones every few days, this battery-free solution certainly seems appealing.