Review: Sennheiser MM 550-X

You may recognize these Sennheisers, since we reviewed the previous model about a year ago. But they've been updated recently with some new firmware that gives them better audio. They look exactly the same, but there's a new model number: They're now called the MM 550-X.

The MM 550-Xs are Bluetooth headphones. They pair with a phone easily, they charge over USB, and they fold up into a highly portable bundle. The controls are all on the right earcup, and they're pretty simple to operate. There's also a pass-through feature – just press a button on the earcup and you can hear what's going on around you without taking the headphones off.

The enhancement here over last year's model is added support for the Apt-X codec, a form of lossless compression that lets you transmit hi-fi audio wirelessly over Bluetooth. You'll need an Apt-X-compatible device to take advantage of this better-sounding wireless connection, but I got it to work on a MacBook Air and an HTC One X (Sennheiser lists compatible devices on its website). Unlike most forms of audio compression I've heard in wireless gear, Apt-X is very forgiving and gentle. The audio suffers from no discernible degradation before it reaches your ears. If your source isn't Apt-X compatible (like my iPhone 4), the default of SBC Bluetooth 2.1 is used, which sounds fine.

This all adds up to an awesome pair of headphones. They're very light, super compact, and the over-the-ear design is really comfortable for long periods. The noise-canceling technology isn't super-silent, so you hear some ambient noise in the background while you're walking around listening to music. But if you're a purist, that's a good thing – it means your music will still sound very close to what the artist intended. So, these are the headphones I'd recommend to people who typically dislike noise-canceling, or for those skeptical about wireless audio.

They're really pricey though, about $500. You can find them cheaper if you shop around, but that's still a lot of money, even for wireless noise-canceling travel headphones. One other thing: They're too quiet for truly noisy situations. I wore them on a belching diesel-powered bus and I couldn't get them to turn up loud enough.

WIRED Stellar sound, even with noise-canceling activated. Support for hi-fi Apt-X codec. Super-portable, wireless design makes them perfect for all kinds of travel. Over-the-ear design stays put, keeps a good seal and feels great all day.

TIRED A whole lotta drachmas. Controls can be confusing – RTFM before use. Could definitely do with some more headroom.