In case you've never heard of KEF, it's a British company that makes premium speakers that generally sound really good. Those speakers tend to be a bit pricey -- and some are very pricey -- but now the company has made a foray into the headphone market with two new models, the $300 on-ear M500 reviewed here and the $200 M200 headphones, which sound great but won't fit everyone equally well.
The first thing I'll say about the M500 is that it's one of the most comfortable on-ear headphones I've tested, ranking up there with the Bose OE2i. Like the Bose, this KEF has memory foam in the "breathable" earpads, and those pads rest nicely on your ears, sealing out a decent amount of ambient noise without feeling too snug. KEF says the headphones conform to the shape of your head, "sitting neither too tight nor too loose," and I'm happy to report that the M500s deliver on that promise.
Just as importantly, the headphones have excellent build quality, with a lightweight aluminum frame and KEF's multidirectional Smart Hinge, which allows you to lay the headphones down flat or fold them up for storage in their included carrying case (it's nice). The one small issue I noticed is that Smart Hinge does have some screws in it and one of the screws started to come out in my review sample after about two weeks of use. Luckily, I noticed it, and managed to screw it back in with a tiny screwdriver (it's a Torx screw but if you have one of those tiny screw drivers for eyeglasses, it'll turn the screw).
That loosened screw didn't dampen my enthusiasm for the overall design of the product. The M500s succeed in having a unique look that's sleek, modern, and stylish in an understated way. In that regard, they're similar to Bowers & Wilkins' popular P5 headphones, which have a striking design while managing to be reserved. Comparing the two, I'd say the M500s are a bit more comfortable, but like any on-ear or over-the-ear model, they will get your ears a little steamy if you're walking around with them on warmer days.
Along with the carrying case, you get two detachable cords, one of which has an integrated remote/microphone for making cell phone calls (the remote is made for Apple devices, so some of its functions won't work with Android and other smartphones, though you should be able to use the microphone for calls). Both cords have a flat, tangle-resistant design, and I liked how they connect to the headphones on the backside of the aluminum. I caught the cable on a door handle once and the cable detached from the headphone without incident (and by that I mean the headphones weren't damaged).
How do they sound? Very good. As I said in my review of the M200s, this model has bigger bass and while I preferred the sound of the M200s, the M500s are still quite good but different -- and some people will prefer their sound over the M200s'. The M200s are a little more accurate and have a slightly more forward, immediate sound. But the M500s are relatively well-balanced, accurate, and open headphones that offer good detail and are pleasant to listen to for long periods.