Pros: Spacious, yummy bass, and exacting highs. Enjoyable equally for music, gaming, and movies. Very comfy. Very good price-to-performance.
Cons: Some may find the highs fatiguing, and they can take a bit to get used to. Cable can be a bit much and isn't detachable.
This review is an expansion of my comments in the D2000/5000/7000 thread. I wanted to spend a bit more time with them, and ultimately these have become my daily driver. I've gone through many headphones, and these honestly are among my favourite. I love how they sound like an open set of headphone thanks to the Acoustic Optimizer (you'll see the space between the cups). This is one of the hallmarks of the Denon AH-Dx000 series (and by extension the Fostex TH-x00/600/610/900, E-mu Teak). Not only do you get an incredibly spacious sound, but the advantages of back pressure for the bass range gives this series some low-end punch. The bio-cellulose drivers are quick. not as quick as the planar magnetic but quite close. There is definitely a sonic character to these that I haven't heard elsewhere (well the AH-D600 also had this but I prefer the AH-D2000).
Here are some comparisons to the HD650, Sony MDR-7520, and Audeze LCD2.
Comparisons to HD650
These make my HD650 sound very sleepy. And its easy to see why by looking at the frequency graphs. In comparison to the HD650, the Denons mid-range around the 1khz level is quite lifted. The reason for this is prior to 1kHz the 650 has an elevated mid-bass and lower mid-range hump, whereas the D2000 is considerably flatter. Also the upper frequencies of the D2000 are more in line with its lower and mid range frequencies. The result is that the D2000 is much sharper sounding. The 650s sounds a bit cloudy - not congested - just darker.
No doubt, the HD650s are much easier on the ears and you just sink into them after a couple minutes of listening. The 650s could be listened to ad infinitum without fatigue. I also may prefer the 650s upper mid-range over the Denon. The HD650 delivers that velvety-lushness while still retaining some detail which makes it such a classic. Comfort, the 650 still wins.
One thing that makes a massive difference for any testing, is listening volume. The D2000 isn't a headphone I'd want to crank up without eq. The HD650, you could crank up. The D2000 can produce listening fatigue centred right in that 512Hz-1khz range at louder volumes. The D2000 is brilliant at a lower/average listening volume, and its there that they sound more realistic. It probably can replace my 650s functionally for what I use them for - movies, gaming, lounging about, direct listening from iPod, piano practise.
The D2000s actually replaced my HD650 as my daily driver. The HD650 is an excellent headphone, but I felt that the D2000 beat it out for practicality (easy to drive, closed design brought more privacy) and sonically (the Denon had more tactile bass extending further, and the highs on the Denon brought clarity that was just too blanketed on the 650). I've owned the 650 twice, and feel that I'll be reunited with them at some point again. They are one of my favourite headphones, and even more than the LCD2, make everything easy to listen to. I didn't need two open headphones and between the LCD2 and the 650 I felt I still need to spend time the LCD2. Hoping Sennheiser updates the 650 design in a better build in the future. Perhaps I should be looking at the HD800S. :)
Comparisons to Sony MDR-7520
Compared to the Sony MDR-7520 the Sony sounds much more closed yet still impressively detailed. Some may find it 'boxy' but for those of us used to listening to studio cans, this is a familiar effect of their signature. The brain acclimates to them pretty quickly, and soon you start listening to the depth of the music even though it doesn't seem as wide as the D2000. It is much less spacious than the Denon, particularly as it isn't doing any 'tricks' with its frequency range. And it shouldn't, as its designed as a proper studio headphone for mixing purposes. The 7520 has very good bass, and is definitely more accented. The D2000 has a bit more sparkle and sizzle, whereas the 7520 is flatter.
Comfort wise, the Denon is a winner here, and that is one of the main reasons I picked it up - I was looking for a more comfy closed can. Its more because of my large ears, otherwise I think the 7520 is actually a very good fit. The Sony is a lot more portable and also has a removable cable. Build-wise the 7520 is more rugged - with magnesium cups and a very simple but sturdy headband.
I'm going to try not to be biased with 'new toy syndrome' and I'll say that the 7520 gives the D2000 some competition. It seems that somehow the Sony is smoother in the upper mid-range. I do feel that the 7520 is more faithful to what is being recorded but the D2000 is more faithful to what is intended on being reproduced.
However, the 7520 can be largely listened to without fatigue. Those highs aren't nearly as sharp as the D2000. In my review of the 7520 I felt its performance was incredible, even against the HD650 and my LCD2.
Going back to the D2000 from the 7520 instantly opens up the sound. Everything separates and becomes more spacious. Overall, I'd put the D2000 ahead for music enjoyment, and the 7520 has its place as a studio tool or street headphone.
Comparisons from memory
I used to own a Denon AH-D600 and I don't recall it being as spacious as the D2000. I believe its bass was elevated a bit more, but overall the D2000 sounds a bit more linear, and less artificial in the upper registers. That said the D600 was still a very good and even more comfy. The D600 could also be said to have a friendlier signature.
Logitech Ultimate Ears UE6000 - The UE6000 have much more bass than the D2000 and overall have a dark tilt to their signature. The D2000 have a much more refined sonic presentation. You can listen to classical on the Denons, whereas its mush with the UE6000 (still a good can, just more for pop and bass music).
Beyerdynamic T5p - I really liked that headphone. There again is a headphone that some thought was too bright but I really enjoyed them. Didn't feel they were too bass light either. The fit on the T5p was very good, same with the build. Still, from a price perspective, I picked up the D2000 for a 1/4 of the price, and I really feel they compete sonically with the T5p. Funds permitting, I'd love to try out the DT1770, T5p 2nd edition, and T1 2nd edition.
Some LCD2 comparisons
I remember listening to a TH900 at an event and being impressed. Not replace my LCD2 impressed (though close). Now I feel that I have a bit of that magic, of course, for much much less.
The LCD2 are some serious head gear compared to the rest. I've grown accustomed to their fit. But, the D2000s are ultimately easier to deal with. Even though the D2000 cable isn't perfect, it isn't stiff like me early LCD2.1.
Sonically, the LCD2 seem to mix the best from both the 650 and the D2000. They also have the edge on overall clarity. Yeah, they aren't going anywhere. Impressively, I'd say the D2000 is quite close to LCD2 in presentation, with a bit more added presence. The LCD2 have a bit more 'meaty' sound to them. Oh, and with the D2000 soundstage isn't even that much less than the LCD2! LCD2 on a budget? Honestly, I feel the bio-cellulose drivers compete very well with the planar magnetic drivers of the LCD2. I also find the LCD2 could use a lift in the high-end and the low-end and the D2000 has a presentation that I prefer for most listening.
Put it this way. The D2000 has made me consider parting with LCD2, HD650 (gone), possibly my MDR-7550 in-ears. I'd keep the 7520 for studio reasons and outdoor portability. For open I might get an HD800 to replace the rest. Not quite sure, and when I put on the LCD2 I appreciate them. I'm not going to rush that decision. Either way, the D2000 is getting the majority of my listening time right now.
Binaural audio test (using Naturespace app on iOS)
Lastly, I tested the D2000 with some binaural recordings of nature. My HD650 has always been the best in this test. The D2000 while not quite as natural and relaxed sounding as the 650 faired well and in some ways better in binaural listening tests. They bring some of the energy on the top-end that the 650 lacked. They are quite realistic, again due in large part to the linearity of the D2000 through most of the frequency range. Would need to test more before declaring a victor but I'm edging towards the HD650 - something sounds more complete.
In a lot of ways, this inexpensive headphone is kind of endgame for me. In many ways this is what I've wanted from a headphone, especially a closed headphone. You can lock the outside sounds of the world away, be encompassed by your music with all of its details, and admire the overall design.
I guess I'll have to check out the Fostex models and will especially be keeping an ear out for the new Denon AH-D7200. I have a feeling I'd find the D2000 largely give you the performance of many of its siblings without the expense.