"Senns," as they are called in the audiophile world, are major players in the headphone market, and I trust their quality. I have an open pair, the HD-598, which are my favorite. I also own the less pricey 239 model, which are also circumaural and open-backed. The vented (open) design allows air to escape and the sound to be more natural (not noise canceling), allowing more nuanced, ambient sound in without ever getting distortion.
I don't have the language of these technical experts that are reviewing the same headphones here, so consider my review as basic, from a lay person's viewpoint (but I am a lover of sound!). On the other hand, I am baffled that some reviewers are comparing these to the HD-598 cans. Open-back is a whole different experience, which allows outside sound to leak in. I prefer them when intensely listening to music--whether rock, jazz, or blues. These Momentums are also circumaural (covering the whole ear), but closed-back.
In my humble opinion, the Momentums should be compared--for purposes of reviewing--to others in its type. Now, I believe that open-backed are generally superior, as they are designed for subtlety and naturalness, but my review reflects my expectations of closed-back cans.
I consider my ears to be medium-sized for a woman, and these fit me perfectly. Even when I wear glasses, the fit is superb. Some of the reviewers complain that these are too small for their ears; in that case, I can understand the sound being inferior for them. If the Momentum fit is ON your ear (supra-aural), instead of the way they are intended (over the ear), then the design of the Momentums will not be as intended for your ears. I agree that these could have had a bigger circumference. Most men are not going to have small enough ears for these to fit circumaurally. They are definitely smaller around than my 598s. One thing I have learned by experience is that if the cans don't fit, the sound won't be "it."
I broke these in for 72 hours. I use these a lot for movies and for casually listening to music. The sound is warm rather than bright, but I get a lot of clarity when listening to dialogue. If I am in the mood for The Dark Side Of The Moon - Experience Version, or Emerson Lake & Palmer - Brain Salad Surgery (DVD Audio), I will switch to my 598 open cans, definitely. However, the Momentums are perfectly capable, with strong and resonant treble, if I am in the mood for Steely Dan's Pretzel Logic, Billie Holiday Love Songs, Louis Armstrong's Definitive Collection or any of my classical music collections. These provide ample sound separation and rich texture. Movie sound is pretty nice and tight, too. I experienced no fatigue and am able to wear these for many hours.
As for construction, these are works of art. The ear pads are made from luxurious leather from British manufacturer Pittards and are a sensual delight on the sensitive ears. The mix with metal is a sexy combo. The sturdy hard shell brown case will protect the cans, and is handsome and lightweight to carry. I would probably not carry these around much, though, because I have smaller Senns that I can tote for my ipad/ipod. I will keep these for home. 4.5 stars rounded up.
"If music be the food of love, play on;
Give me excess of it..."--Duke Orsino, Shakespeare's Twelfth Night, 1602
"We all go Do, Re, Mi, but you've gotta find all the other notes yourself."
― Louis Armstrong