The NDH30 released in spring last year, and I've been quite interested in them for some time. They measure reasonably well, they look good, they seem well-built... so I had to get my hands on them. Reviews have been mixed, with some (but not just the usual suspects) calling them excellent and comparing them favorably to Sennheisers 600 series, but with other reviewers finding them somewhat dull or unimpressive.

First thing: I can only praise the build quality on these. They make even the DT 1990 Pro (which is admittedly quite a bit cheaper) feel a bit flimsy in comparison. Everything feels both very robust and yet pleasant to use. They can be folded up and the cups can be rotated a full 90 degrees to lay them flat on the table. Many have commented on the weird choice to have a right-side cable, but I can't really complain, the cable is cloth-covered and pleasant anyways.

However, when it comes to comfort, I have to make a few criticisms. The earcups are deep and large enough for me (better than the HD 600 series), but the earpads are slightly too stiff for my taste (keep in mind that I wear glasses, so YMMV). The biggest problem is the headband cushion though, it is not soft or large enough and they get uncomfortable after prolonged time. Overall, comfort is OK but not as good as my Beyerdynamics.

But the important part which we're all here for is the sound. I'll make comparisons to the HD 650 and the DT 1990 Pro (which I've sold by now). The NDH has a generally slightly warm lower end with a bass that extends well for an open-back headphone. It has enough weight to make drums sound good and properly deliver electronic bass, though it is far from a bass-head headphone. The lower mids are warm, but not warm enough to lose clarity. Beyond the lower end however, vocals seem slightly laid back compared to the HD 650, and the tuning is dark overall. There is absolutely no sibilance or harshness in the highs. I can understand why some have described them as a bit dull, some instruments (cymbals, some guitars etc.) are lacking edge a bit. One point that elevates the NDH for me is the good imaging and reasonable soundstage: it is significantly better than both the DT 1990 and the HD 650. Sounds do not sound "far away" as they do on a HD 800, but they have noticeable space and the positions of instruments and vocals can be heard very well.

There's one big caveat though: the NDH can sound very, very different, depending on where it is positioned relatively to the ears (probably due to the angled drivers). I've described the "natural" position for my head. However, if I push the headphone forward on my head (so that my ears are at the back of the cup), the sound becomes extremely dark and hollow. In contrast, in the opposite position (with my ears at the very front of the cup), they have far less soundstage and noticeable treble (and are even slightly shouty). This can, for some cases, account for the very different impressions reviewers have had of these.

Personally, I was looking at the NDH as a replacement for my DT 1990, which I found too sibilant for prolonged use when not EQed. I've demoed them before, but always just for less than half an hour, and wearing them for a few hours is something entirely different. I particularly enjoyed them for the "harder" subgenres of rock or for metal, as well as for some electronic music. Besides its lack of subbass, the HD 650 sometimes feels a bit blurry and muddy for faster songs, and the lack of soundstage can make it a bit too intimate. The NDH delivers on this very well, since its lower end is less muddy in comparison. However, it's not a solution for everything: a lot of metal sounds disappointingly bad on basically any good headphone, except when played very loud, but the NDH is so far my most enjoyable headphone for these genres. Overall I have to agree with the criticisms of the dark tonality though. A slight bit more upper mids/treble would've really elevated its tonality. The way it is now it is pretty much a slightly improved HD 650.

Sadly, I have to conclude that the NDH 30 offers too little above the HD 650 (slightly better lower end and good soundstage & imaging at the cost of being a bit more dull) to really make it worth the price from a purely sound-based perspective. It probably is the far more suitable headphone for music production, but for simple consumption, it offers little more than the 600 series. It's main upside is the excellent build quality and the (to me) slightly improved comfort.

This leaves my slightly disappointed since it seems more like a side-grade than an upgrade (in sound quality). That said, I've accidentally bought an HD 800S recently, so I'll get some kind of upgrade in any case.