Pros:Well-made, comfortable, very effective noise canceling. Great sound!
Cons:Battery pack "dongle" gets in the way. Circuitry doesn't magically reduce all noise.
The Bottom Line: A great product for commuters. Well-made, nice sound, and effective noise cancelling. But try-before-you-buy to see if these are right for you.
I purchased these headphones in late 2005 because of noisy commutes I make for work. I highway-drive and fly quite frequently, and wanted to listen to music without ambient noise. I researched NC (noise-canceling) headphones on the Internet, and decided to take the plunge. I bought the Sennheiser PXC250's at BestBuy, mostly due to their generous return policy (in case I didn't like them).
Recommend this product?
I think it might be worth mentioning that I am a college music instructor, with years of formal music training. I also have a good-quality stereo system at home, as well as numerous other pairs of headphones (AKG, Grado, Sony) and would consider myself a pretty critical music enthusiast.
Like many other net reviewers, I found the PCX250's to be well-made and well-designed. They're comfortable to wear. I also found that even though they aren't a "fully enclosed" design (i.e. they don't physically cover your ear, but rather just rest against them) they isolate the world around you pretty well. This also makes them more comfortable than 100% closed designs.
However, the NC battery pack is somewhat of a beast. Not very friendly. I found some cord management issues, and there's no way you'd want to exercise/jog/move around excessively with this thing. These headphones seemed to be designed for commuting, resting, staying-in-place.
On to the sound!
Well, to be honest, the sound WITHOUT the NC turned on was pretty mediocre. It still sounded OK, and would be tolerable for different applications, but there was a distinct lack of lows and low-mids. There was also a lack of intensity (i.e. the volume was low) and I couldn't really imagine any circumstances in which you'd want to use them in this manner.
Then, I turned the NC circuit ON. Quite amazing! The NC very suddenly eliminated most the ambient street noise around me. A very noticeable difference. Again, like others have mentioned, you STILL hear what's going around you (especially mid-to-high frequency sounds) but the general rumble and roar of the city is GONE! The NC introduces a slight "hiss" of its own when it is turned on, but it wasn't objectionable.
With music turned on, the isolation from the world is even more pronounced. The pre-amp circuitry seems to accentuate lows and low-mids, but the high frequencies are quite nicely done as well. The overall sound of the PXC250's is very pleasant to listen to -- not as bright as Grados, or even the consumer-level Panasonic headphones I have, but well-balanced across the spectrum.
Moral of the story: well, I eventually returned these headphones and bought a pair of the fabled "Etymotic 6i" in-ear headphones. Why? Well, I think the PXC250's would be great for business/recreational users who DISLIKE wearing earplugs or in-ear headphones. The PXC250's are comfortable, well-made, easy-to-use, and very effective at "doing what they do". However, they didn't reduce ambient noise enough to my liking. Not for $200 CDN. Plus, I didn't like the battery-pack dongle that hung from the cord. This is where the Etymotic series completely wins: these 'phones are microscopically small, reduce ambient noise by over 25dB, and sound great. But again -- choosing the right headphones depends on your usage and habits.