I've been using the NDH30 for almost 3 months. Here are my thoughts:
Comfort and build
I like how they look (I'm one of the few who still prefer the silver version over the newer black one). They feel like a premium product. The earpads are one of the most comfortable with a 65mm inner diameter and around 22-27mm depth (22 in front where the driver is, 27 behind the cloth where the ear is). I like how soft the velour material is - I'm very sensitive to itchiness and I don't have any issues here. I also find the shape and softness of the foam to be perfect for my head and ears. And the clamping is on the looser side but it's tight enough for the secure fit. I don't feel like they're going to fall off. They're pretty light (367g) with decently large earpads so you don't really need much clamping for the stable fit. They have also very good ergonomics. I'm probably weird but I actually like the cable being on the right, because I also have my amp on the right side of my monitor. And I like that they can fold flat - useful for cleaning the earpads. Although, I would prefer them to fold in the other direction.
I have only 2 complaints:
- The headband padding is not very good. It's alright from the beginning but in longer listening sessions I can feel those 2 spots on my head. Not that it's stiff - it's pretty soft actually, but the contact area is so small it doesn't distribute the weight very well. It reminds me of the DT900 PRO X. I also don't like that there is rubber on the sides of the headband.
- The cable is pretty bad. It's too long, a bit microphonic, a bit stiff, and the termination is really bad - it's covered in rubber so it feels really cheap and the adapter to 6.3mm won't stop screwing. You can screw it infinitely. So sometimes I have issues with sound cutting or rather sounding weird and then I realize there is something wrong with the cable and I have to play around with the termination to get it back. At this point, I found the position where it works so it didn't happen for a time now, but still pretty annoying. The worst thing is that the hole for the cable on the headphone is really small so the M40X cable won't fit. So I got used to the stock cable. I mean, it's not the worst so it's still usable.
In terms of isolation, it's what you would expect from a semi-open headphone. They're slightly more open than K712 or DT1990 and DT900 PRO X, but more closed than most open-backs. That also doesn't help when it comes to cable microphonics. It reminds me of X2HR in this regard. I don't have them anymore to directly compare but I remember them also being less open and having clothed microphonic cable.
Sound
They're about as hard to drive as HD660S2. Or at least they sound about as loud on the same volume with a linear source.
The overall tonality is solid but not perfect. When I was reading about them, I was really confused because some people were complaining that they were too dark and some that they were too bright. Now I understand why. The treble is a bit unbalanced - the lower treble is emphasized and there's not much air in the upper treble so depending on the content you're listening to, they can sometimes sound too dark and sometimes too bright. But most of the time, they sound relatively neutral.
I also read that depending on the position on your head, the treble will sound different. I tried to move them around and while yes, when I put them completely back or completely in front I can hear a difference, but that kind of fit is very uncomfortable so why would anybody do that? While wearing them normally, I couldn't notice any difference when moving them around slightly. Also, because of their design where pads are deeper right behind the driver, there isn't really any more space where you can move them before making it uncomfortable. So I wasn't able to reproduce this issue on my head, or at least not in realistic conditions.
I would describe their tonal balance as Harman-neutral. There's quite a lot of bass for not being a closed-back, they're a bit too bright in the lower treble and too dark in the upper treble. So they sound a bit shouty, glaring, harsh, tense, and fatiguing because that lower treble is always in your face while there's not much sharpness in the very top end making them kind of sound like behind a blanket.
NDH30 on Gras (Oratory) against the preliminary target until we get the correct DF
Their presentation reminds me of DT1990 by having a very intense kind of sound but also with that sense of contrast. They sound lively, engaging, and pretty detailed like they want to force all the details in your ears. But it doesn't sound sibilant, for the most part. You get that underlining thump from impulsive low-end and snappy transience from the transparent lower treble.
Spatial qualities are also what stands out on them. They don't have the best soundstage or the best imaging I've heard, but a very good combination of both. I would compare them to R70X or K712. You get that surrounding kind of experience which is pretty satisfying. They have also a very good sense of depth and scale. Only when the tonality doesn't work for the content they can get a bit claustrophobic and focused because of that tension.
Use case and conclusion
They're not my favorite for busy music because of that harshness, but where they really stand out is orchestral/epic/OST music. I also like them quite a lot for hip-hop. But they also sound pretty good for anything that can use that extra sense of contrast, like rock and metal. I just need to always "recalibrate" my brain for the brighter ear gain. The vocals are also very good. Not as good as HD600 but pretty close. Most importantly, they have that "ethereal quality" when it comes to instruments. Especially the pianos and orchestral instruments. Some people were comparing them to ZMF headphones so now I really want to try the Auteur Classic :)
They're also pretty good for competitive shooters. Not my first pick but one of the best for sure.
When it comes to immersion and ASMR, I find them too harsh and fatiguing for both. They're not bad, just not what I would use.
If you didn't know, NDH30 uses the same driver as HD560S, so there are some similarities in their sound, like the spatial presentation and some tuning features, or that intense kind of sound. But while I'm not a fan of 560S, I'm really impressed with the NDH30. It's a good example of how the driver itself doesn't mean anything. It's about how it works together with the acoustics. NDH30 is basically what 560S was supposed to be.
NDH30 is one of those headphones that made me think about selling most of my collection when I first heard them. Now I know that there are flaws, but even after a few months, it's still one of my favorite headphones. Although, there is one headphone I sold because of the NDH30. I finally found something that took the K712 off my throne for orchestral music. I tried so many headphones but there was always something special about K712, so they still held their position as my favorite for that kind of music. Until I tried NDH30.
I can highly recommend the NDH30.
Some examples of what sounds the best on them:
this kind of music