I doubt you'll find much information on most active NC cans over here as most audiophiles (which consists of quite a bit of the overall population in this forum) will shun it due to its own ambient noise it creates. Any short term bumping will most likely prove to be futile on your part, just saying.
Hey, I may be the only one on Head-Fi who has 'em...but I do.
And they're great for what they're supposed to do.
Here's my review.
First of all, I had the new Sony NC500Ds for a while. Four bills! They weren't cheap. But...great noise canceling. And great looking headphones. Over-ear design, fit great, very comfortable. I thought I had a keeper...until I cranked them up and the bass started clipping. Clipping bad. I love bass, and one of my favorite reference songs is 'Underneath it All' by No Doubt. The Sonys couldn't handle it. The drivers would pop badly on the bass lines, and I wasn't even cranking them up that loud. So they went back. Bummer.
So I bought the Denons.
I read some good reviews on the Denons, but as so often happens with HP reviews, many of them reached totally opposite conclusions.
One would say...'Great sound IF you use the noise cancelling.'
Another would say, 'Great sound if you turn the noise cancelling off...' As you'll see, I tend to agree with the latter.
My first impressions were they were beautiful looking phones. Very elegant, simple, understated. And as you know, they're on-ear, not over-ear.
Trying them on, I was disappointed the sliders didn't go further. I have to wear them with the sliders all the way out...and they fit, but barely. If you have a big head...they might not fit you. But I have a huge head, as in 99% of baseball caps will not fit me...and I can wear them.
My thought...using the Meier Corda 3Move as my amp...they're wonderful with the noise cancelling off. The bass is very, very deep and fat. lots of power, lots of definition. Obviously not as much as my Denon 2000's, but it's there.
On Avril Lavigne's 'Sk8r Boi,' the sub hits in the beginning of the song are deep and medium-powerful. Some phones can't even hear 'em. But the Denons do...although the sub hits don't have the heft they do with the Denon 2000's. With the above-mentioned song by No Doubt...the bass sounds great! Fat and powerful. And on the Denons the drivers have never clipped, and I've turned them up so loud I was afraid I'd hurt my hearing. The drivers really hang in there.
The highs are nice and sparkly, very defined. The mids are somewhat recessed, but not too badly. I mean, on crunchy electric guitars they're no Grado....but they don't disappear either. Example: on Ingrid Michaelson's 'The Way I Am,' the bongos have a small touch of reverb, which you can hear on good phones, but not on these. You hear the notes as the fingers hit the skins, but no real warmth and presence.
Overall, with the n/c off and using the 3Move, they're very, very pleasant HP's to listen to. It's a nice balanced sound. Lots of bass but not overpowering, very clear and fun. Very, very low distortion. Clean.
Now, with the noise canceling on...they change. The highs get very sharp and intense...sibilance raises its ugly head, slightly...some of that 'sssssss' on singer's 's's' and cymbals. The bass also gets much bigger and more powerful...kind of sloppy, but not toooo bad......and the mids get kind of left behind. Less present that with the n/c off. And distortion rises a touch.
But I imagine you'd only use the n/c if you had to. And they do a nice job at noise canceling. Not quite as 'silent' as the Sonys were...but they still wipe out the low, loud drone on the DC Metro very well. Again, with these you won't get silence. But you will get a much, much quieter environment and the music comes through better. Maybe when competing with external noise, the sharper highs and more pronounced bass is a good thing...kind of cuts through the stuff happening around you better.
The soundstage, with the n/c either on or off, is average. I had some 880's, and that was a soundstage. These can't compete. The various instruments are more like, left and right, than all around you.
Before I wrap up, let me also say I don't know anything about IEM's. I'd like to try some good ones but I never have.
Price: Got them at B&H for exactly half of what the Sonys sold for. A bargain.
Comfort: They're pretty light, and they hug well on your head. Using them for long periods, they feel fine. More fatiguing with the n/c on...probably because of those pronounced highs and bass.
Case: Beautiful...and about 1/4 the size of the Sony's. Very elegant, very simple. Two-length cables, plus the expected 1/4" adapter and airplane jack adapter.
I'll keep them. They'll never replace real audiophile headphones, like the D2000's, or the D7000's I have on order. But, they do what they're supposed to do. When I'm taking a trip they'll come with me. I'll use them on the plane, on the Metro using n/c. And later, in the hotel, I'll listen to music on my laptop or iPod with the 3Move and n/c off.
And when I get back home, they'll go into my drawer and I'll listen to the real deal.
All the great reviews at Amazon tempted me into buying these headphones. I agree with most of what HD_Dude already wrote. They sound great with NC turn-on except for slightly weaker bass. Without NC, bass is slightly on the stronger side but they still sound awesome and probably would have been my choice for ONE over the head headphone that has it all. But unfortunately, I so far didn't like the comfort of them as the phones rest on the ear and initially I had a feel that they would bother me if I had to listen music with them for long hours. I tried out Sony MDR-NC60 in Sony store. I only paid attention to the comfort and then and I felt they are incredibly comfortable compared to Denon for long hours of listening.
I ordered Sony MDR-NC60 as well as I got a great deal on a refurbs through a friend who works at Sony ($44).
Once I have them I will compare both and will decide which one too keep. I might just hang in with both in case my wife needs them on long journey's. I paid ony $100 for Denon at Amazon's Warehousedeals.com (Open box) as the 1/4" adapter was missing in the package.