Even at first glance, it can be glaringly obvious that Head-fi in general isn't a fan of Active Noise Canceling Cans, and there are valid reasons for this; for one, the active NC module is prone to creating noise and distortion in sound on its own, and for two, there simply aren't too many good ones around. You'll have majority of the posters here often throw their hands up in the air and say "go for Bose Quietcomforts if you must go for Active NC can", which really shows the lack of good quality NC cans in general.
I was also one of the doubters that refused to believe that an Active NC can can sound decent, and I had a reason for basis... back in the pre Head-fi days, I had tried the Sennheiser PXC150 hoping that it would give me decent noise canceling and also provide a PX100-ish type of sound. Boy, was I ever wrong... Not only was the Headphone on its own crappy, the noise canceling module itself was almost big as a ******* glowstick, and was very poor at noise canceling as well, faltering under the heavy traffic noises here in downtown Toronto (this lead me to buy a passive NC headphone, which lead me to SE210 and in turn, here to this forum).
Flashback to present, or to be precise, three weeks ago, I happened to stumble onto a local Denon Warehouse sale, in which I hoped to pick up some D2000's or 5000's. Unfortunately, those were sold out, but another headphone caught my eye. NC732. It wasn't so much because they were noise canceling (my SE530's did more than adequate job of that), but because of the price... $99 CANADIAN. That is the cheapest I've seen a NC can that isn't a low end JVC, Sony, Coby, or what have you. Knowing Denon's reputation and thinking how much I've enjoyed the D1001 so far, I figured "What the heck, for $99, I have to bite". Three weeks later, I bring this review to you, after 80 hour burn in and extensive testing with the NC module both on and off.
To sum it up, these are actually very decent for a NC can, ESPECIALLY at a price I got it for. It has its weaknesses, but it has several key strengths and does what it is advertised to do, noise canceling, very well. I'm going to divide up the review to aesthetics/bundled accessories section, a comfort section, Noise Canceling section, and a SQ section by different areas of the Frequency range, with both NC module on and off. Alright, so here we go.
[size=x-large]Aesthetics/accessories[/size]
Upon first look, these look like a blatant ripoff of the Bose Quietcomforts (the On-Ear model, the QC3, I believe?). They really do. They really resemble the QC's in overall shape and design, with the major difference being that this is entirely black coloured (sans the oval chrome trim on the cups) compared to QC's silver cups. I'm not sure whether or not QC's fold, but these fold away to a compact size, ready to be tucked away into the bundled semi-hard case (more on the case later). The cups themselves can be turned 45 degrees inwards, although this is mainly because it needs to be tucked away and not because you'll do one ear monitoring or anything (not that you want to do that with these). The NC switch is located on the right earcup, fairly inconspicuous on its own, but accompanied by a blue LED light that some people may find annoying (I know a few who do). On the left earcup there is a plug slot for the detachable cable, which is actually just a glorified/lengthified mini-to-mini plug. They don't detach too easily, and would never come loose on its own, but a hard yank will definitely pull these off of course.
Denon was kind enough to include two different mini-to-mini cables, one that terminate into a L-plug and one that ends in a straight, presumably iphone compatible plug (I don't have a Iphone so I wouldn't know). I know Denon doesn't have a good rep with their standard cables, so it may be possible to increase the SQ of these with a better cable, who knows. it also comes with the aforementioned paperback-sized case, which is reinforced with hard rubber. It is very sturdy and I feel very confident that this case can protect the headphones very well. There are also few zipped pockets inside which you can use to tuck away your cables or what have you. Also comes with the standard /8 to 1/4 plug adaptor, but I got literally dozens of those now. Meh. Anyways, I give them 9/10 for aesthetics and extras; it certainly looks very sharp and you can't complain about the quality extras they bundle with it.
[size=x-large]Comfort[/size]
These are fairly comfortable for an on-ear. The cups themselves are on-ear with the groove in the centre, fairly standard and HD25-ish. One thing I want to mention here is that the grooved cups themselves create a sort of a vacuum-seal in your ears, kinda like the sensations you'd normally associate with IEM's. This helps immensely with isolation which I'll get into more detail later, but some may find this sensation uncomfortable. The headband doesn't clamp too hard, is sturdy, and doesn't exert too much pressure at all. The pads are made with pleather as seen in D1001, and just as comfortable. Quite honestly, this is how D1001's would feel if they were on ear, and that's a good thing. Of course, in an extended session, these get very hot on your ears, but it was at least beneficial here in the cold, wintery weather of Toronto, Canada, where they acted as my earmugs. Heh.
[size=x-large]Noise Canceling[/size]
Without a doubt a very important section, since this is their namesake after all. There is nothing worse than a Active NC can that can't even isolate well (like PXC150), since they usually don't even sound good. Denon states on the box that it cancels upto 99% of ambient noise, which is a very bold statement... and it indeed is, but I can testify that these are by far the best Active Noise Canceling that I've had a chance to use, and that includes the Quietcomfort 2 (which I had a chance to demo at the Apple store to test out noise canceling). I'm not going to go into the technicality of how Active NC works, since most of you know that already is... but I found that the NC module in these headphones pretty much neutralize most of the low range frequency noise going on around you, I'll be bold and say 85-90%. I've used these in the streets of downtown Toronto by the highway ramp under a bridge with constant truck traffic, which is pretty much the worst noise environment I can think of, and these headphones reduce the truck/car noises down to what sounds like an ocean wave. Yeah, I'm serious, no joke. They're very effective. They don't isolate the high frequency range nearly as well, so you'll at times hear high-sharp pitch noises, but they still isolate those decently as well. Of course, you'll want at least SOME sense of what is going on around you and rarely will you want complete 100% silence. All things considered, the NC module was excellent and has made me a believe in the Active NC technology once more. Another boon here is that these are very much usable even without the NC module on (a big loud "HA!!!" to the Quietcomforts), which leads me to the next section.
[size=x-large]Sound Quality[/size]
Of course, here in Head-fi, if the sound quality fails, the cans fail, no matter how attractive they may be otherwise. In brief, these are not the best sounding cans of the world, but has strengths and improve significantly after a burn in. As I've stated, I'll divide this section into the SQ with NC on and off, describing the main frequency ranges (High, mids, and lows).
[size=large]With NC On[/size]
With these cans being NC cans, you'll obviously use these mostly under these conditions so this is probably more important of the two... first things first, I would like to inform you that the NC technology at work here is very, very quiet. It is definitely not a hiss-fest that I had experienced with the PXC150's. While it is still audible when everything is deathly silent, it is very faint and basically doesn't have any distortion effects once the music is on. Nice. As for soundstage, they're ok for a closed can, really. Would it even be possible to put a respectable soundstage in a close can, a NC one at that? I don't think so, but it's seriously ok here, not wide but pretty 3D-ish. Now, on to the SQ itself...
Highs
Highs are usually the biggest weakness in an Active NC can, though I'm not quite sure why (do feel free to educate me on the technological limitations at work here, if you do know). And unfortunately things are no different here, with the highs experiencing a serious roll-off way at the top. You can EQ to offset this problem to a degree, but obviously EQ is no panacea to rolled-off highs and you will still experience it. Now, it's not completely bad; the low to mid-highs are actually pretty decent, but it's at the very top where it suffers very bad. So you'll find that a male vocalist sound perfectly fine on these 'phones but the female ones sound absolutely awful. They do improve somewhat after burn in, but the highs don't magically appear, either. Treble fans need not apply.
Mids
It's definitely there, but there is definitely a slight veil. You'll feel that its somewhat distant, but you can definitely hear the details of the mids. Mids IIRC isn't a typical (especially lower end) Denon forte so this isn't surprising, but again, it's passable.
Lows
Bass is the well known Denon strength, and they keep the tradition here. The bass is excellent, but ONLY after the burn in. Out of the box, these are very, and I mean VERY boomy and will veil the already veiled mids and rolled off highs, making these almost unlistenable. However, after the burn in, the midbass gets tighter, and lower end gets an exceptional extension... better than my D1001's. The bass extension is equivalent or better than my beloved SE530's, and while those are Balanced Armature IEM's it's still no easy feat IMO. Upper bass is the weakest link here but is still alright. Definitely the biggest strenght of these cans overall.
Overall, I'll give the SQ with NC on 7.5/10. Definitely listenable after some treble EQ-ing and burn in.
[size=large]With NC off[/size]
As stated, these are usable without the NC module off, but this perk (?) also comes with a problem of its own. These are for some reason fairly hard to drive with NC off without an external amp. Off a 1st gen Ipod Touch, I was only able to get decent SQ with volume level at 85%, and it still didn't sound "full". With my T4 (not the best match however, because of its warmness) volume at 6 with high gain and Touch at 60%, I was able to get a very decent volume and overall SQ. Before I go on, I'd like to mention that these are VERY hard to distort even at high volume levels, which is of course a great thing. No matter how much you push these cans, these refuse to distort an inch (I believe there is another review out there which state the same, and it's true). This shows that it may have even more potential with a more powerful amp, so what I state here may not even be with it at full potential.
Highs
Even though the very high end receives a bit of a boost, there is one big problem here; it seems that the NC module work so that it boosts the mid-highs significantly, and it seems quite recessed here with it off. Are highs really that hard to do in an NC can? Pff. I doubt even the most powerful of amping wouldn't do much to help much in this section, which is really too bad because it's definitely its most detrimental weakness.
Mids
Sounds bit more upfront than it was NC'ed. You can hear more detail and it sounds wider. Wooooo.
Lows
Becomes more controlled with the same level of extension, and smears into the mids a bit less. Definitely a pleasure to listen to.
Overall, I'd give the sound without NC the score 6.5/10. I found the sound to be a bit better with the NC on due to it bringing out more mid-highs, but I see the NC-off state having more potential due to is very low level of distortion and bit more prominent mids. It also sounds fairly more neutral than the NC state, I'd have to say.
Well, there you have it. In my opinion, these were a steal for $100 Canadian. It brings a respectable SQ to the Active NC market (although not without obvious weaknesses), not to mention that these IMO look better, is cheaper, more comfortable, and helluva more natural sounding than the Quietcomforts. I also hear that Audio Technica has a respectable offering out there, which I haven't tried, but in any case these are a solid choice for anyone looking at the Active NC market. Overall I'll give these cans a 8/10 score, on my low/mid fi basis
