Both Sennheiser cables terminate in 3.5mm plugs at each end, and both cords feature connectors that can "lock" into the receptacle in the left earcup, so there's no chance they will accidentally fall out. The Momentum headphones' impedance is rated at 18 ohms.
Other accessories include a beautifully finished, cloth-covered hard carrying case and a 6.3mm gold-plated adapter jack. The Momentum comes with a two-year parts-and-labor warranty; proof of purchase is required to make a warranty claim.
The Momentum headphones sound remarkably crisp, clear, and accurate; they don't have the usual bass or midrange emphasis that's common to many headphones designed for use with phones and portable music players. Yes, the Bowers & Wilkins P5 noise-isolating headphones are an obvious competitor, though the P5s have a smaller, on-ear design, while the Momentums are full-size and over the ear. In direct comparisons between the two models, in bass, midrange, and treble clarity the Momentum headphones trounced the P5s, and not by a small amount. The P5s sounded thicker and muddier, the stereo soundstage was narrower, and they were slightly less comfortable to wear.
Brian Eno's ambient tunes from his recent "Small Craft on a Milk Sea" album generated a huge, out-of-head stereo effect on the Momentum headphones, and switching between it and the V-Moda M-100 pair, the sound was very different. The M-100s were tonally darker and more subdued; there was a lot less detail coming from them. Ah, but those V-Moda headphones made a lot more bass than the Momentums. Not that the bass from the Momentums was lightweight or lacking in any way, the M-100s simply have more. While I felt the Momentum headphones' bass level was more accurate and slightly better defined, if you listen to music that sounds best with extra bass, you might prefer the M-100 model. It's a matter of taste.
I also watched a few movies and some of my favorite "Mad Men" episodes, and the Momentums' wide-open sound made it easy to forget I was wearing headphones. In scenes with off-screen action, like phones ringing in other offices, the sound seemed to be coming from far away. That spacious quality may make the Momentum headphones especially attractive to buyers who want to wear them while watching movies.
The Sennheiser Momentum headphones will appeal to audiophiles or anyone looking for full-size, over-the-ear headphones that sound equally good with a wide variety of music genres. Build quality is superb, and the handsome design is a nice alternative to more hip-hop and fashion-oriented headphones like the Beats line. This much I can say for sure: the Momentum headphones are the most accurate I've tested for use with portable devices. However, that also means they probably won't be the right ones for buyers seeking maximum bass power and impact.
Setting aside the small comfort issues I encountered (you may not experience them), these are clearly among the best-sounding headphones in their price class. And for some, they may actually be the best.