We can add another pair to the emerging category of stunning, mobile headphone designs that Bowers & Wilkins and Harman Kardon have helped to define in recent months. But something feels different about the $349.95 (direct) Sennheiser Momentum—it stands out not only from the beautifully designed, high-performance crowd, but also from Sennheiser's own vast lineup of high-quality headphones, which tend to feature a no-nonsense pro-gear aesthetic. The iPhone-friendly Momentum combines beautiful leather, stainless steel, and unique design traits with a frequency response geared towards audiophiles seeking both flat response and attention to lower, sub-bass frequencies. It's expensive, but still manages to win our Editors' Choice award.

Design
The Sennheiser Momentum is a closed, circumaural (over-the-ear) design that fits snugly around the ears. One reason the Momentum stands out from the luxury-oriented headphone crowd is that, unlike the Harman Kardon CL or the Bowers & Wilkins P5 Mobile Hi-Fi Headphones £285 at Amazon UK, it uses brown leather and accents instead of black.

The matte, grayish-brown outer panels of the earcups are contrasted with a shiny stainless steel headband, a gleaming Sennheiser logo, and beautiful brown leather on top of the headband. Like the Harman Kardon CL, the Momentum takes a new approach to headbands, with the ear cushions, not the band itself, being the mobile part of the equation, sliding up and down the lower portion of the band. The ear cushions, also covered in brown leather, are supple and exceedingly comfortable.

The included cables—one with a microphone and iPhone/iOS remote controls for playback, volume, and making calls, and one with no controls at all—are removable and thus replaceable, adding some serious value. Since cables are usually the first part of headphones to go bad, while the drivers are likely still in solid working order, being able to replace a cable often means not having to pay for repairs or replacements.

The cable with the iPhone controls includes a pivoting hinge at the base of the 3.5mm connector, which allows you to adjust the angle at which the cable is pointed. This is useful for when the sound source—say an iPhone—is in a bag or coat pocket, and you want the cable pointing in a different direction than the iPhone is positioned. Not an earth-shattering development in cable technology, but it's a thoughtful design touch that makes the Momentum feel special.

Another nice touch is the sturdy brown zip-up case for the headphones. Despite its beauty, however, is its bulk. The Momentum cannot fold flat—this may be one of its few design shortcomings since it is clearly intended to be used with mobile devices. Regardless, the interior of the case is well built, with a Velcro removable cover to hold the extra cable and included ¼-inch adapter in place. The Momentum looks, feels, and sounds like what I imagine the design team at Philips was hoping to achieve with the Citiscape Uptown . To be fair, the Philips pair is less than half the price of the Momentum.

Performance
Sennheiser has always been great at providing a sense of power in the lower frequencies without boosting the hell out of them like so many current competitors do. (I'm looking at you, Monster Beats by Dr. Dre.) That's why many Sennheiser pairs make great reference headphones for recording—you get an accurate sense of the lower frequencies, even sub-bass sounds, without things getting muddy or unbalanced. The Momentum continues this tradition.

I can't say I prefer the overall audio performance to the awe-inspiring beauty of the Sennheiser HD 558 , but that pair benefits from an open design that adds a heightened sense of spatial presence—and its bulk comes at the cost of its mobility. The HD 558 has no phone controls and is intended for use with home stereos, not walking around town. The Momentum, however, leaves little to complain about—while it lacks the spatial depth of the HD 558, it provides a better overall balance of the frequency range.

On deep bass tracks like the Knife's "Silent Shout," the low frequency electronic bass drum resonates powerfully, but never overwhelms the balance of the overall mix. Importantly, there isn't a hint of distortion on deep bass tracks, even at maximum volumes—levels that no one should be listening at, of course, but a relevant test of what the drivers can withstand.

Instrumental and classical tracks sound fantastic. On John Adams' "The Chairman Dances," the mids and highs are perfectly represented—never harsh, never dull, never too bright, painting an accurate picture of the higher register strings and brass. On this same track, the Harman Kardon CL delivers a slightly more robust bass response, but its highs sound more pinched and nasal in a head-to-head comparison—far less natural than the Momentum. (To be fair, the CL is also $150 less expensive.)

When the lower register strings come in, the Momentum's bass response does not overwhelm, nor does it dissolve in the mix. The lower register brass instruments, with their pulsating pattern, have just the right balance of low-mids and crisp high-mids to deliver a menacing growl. In the era of bass-heavy headphones, the Momentum is far more focused on balance.

Jay-Z and Kanye West's "No Church in the Wild" is another strong beneficiary of the measured approach to the lower frequencies, with the pumping beat shaped far more by its treble-heavy attack than by the low frequenices, while softer, more resonant bass synths underneath the loop receive just the right amount of depth.

Generally speaking, the Momentum is ideal for focusing on content in the high-mids, like vocals, without losing any sense of the powerful bass sounds that often lurk beneath the surface of modern mixes from artists like Radiohead or PJ Harvey. Bill Callahan's track, "Drover," is delivered with an ideal balance between the thunderous potential of the percussion and his unique baritone vocals.

The Sennheiser Momentum delivers something very close to the flat response most audiophiles seek out in speakers and headphones, yet Sennheiser knows this doesn't need to mean the absence of exciting, sub bass frequencies—it just means the bass can't own the mix.

The Harman Kardon CL offers up a bit more low frequency response, if that is what you prefer, and the Bowers & Wilkins P5 and the more affordable B&W P3 SEE IT have a less obvious focus on the high frequencies than the Momentum does. All of these headphones offer quality sound signatures. The Momentum, however, both visually and sonically, is a standout in this group. It's a tad chunky for a pair intended for mobile use, and it's the priciest of the bunch, but it sounds sublime, and earns our Editors' Choice award.

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