Pros: Superb sound quality; full, resounding, controlled bass; warm, rounded mids and good treble, while providing incredible separation and finesse.
Cons: Heavy, clamping force feels a bit too tight, inferior headband design does not distribute force too well. Sibilance in treble for certain instruments.
After over a year of research at Head-Fi and other sources, I finally bit the bullet when I saw the HE-400 at a measly price of $299 on Amazon. In addition to this unit, I also purchased a Schiit Vali and Modi (optical version) after some digging, and reading about people that really enjoyed the Vali/HE-400 combination. Since I'm a neophyte audiophile, take this review with a dose of skepticism; as a disclaimer, I have no experience with high-end machines into the four-five figure range. I am merely a university student who enjoys nice things in life, and quality sound is one of them.
I must say, however, I am enthralled by this budget setup. I am an avid metal and rock fan, as well as requiring my frequent forays into the world of classical music. Not too much electronic stuff these days, although I may get back into them at some point. I listen to a lot of of 'lesser known' bands, even amongst metalheads. Sometimes it's rather difficult to find things in FLAC, which is what I use almost exclusively. I'm too lazy to really bother looking for other formats and uncompressed files. I also prefer to download my music off of Bandcamp, and if the upload quality is ****ty for some reason (the source of the uploader?), I guess I, too, am screwed. But that's alright, I suppose.
My favorite aspect of the headphone is obviously the sound. The presentation and imaging is what I consider excellent, and the bass is brilliant. It is tight, articulate, and controlled. This shows itself very well in metal and rock, particularly in bass-heavy styles with large amounts of low-frequency distortions, 8-string guitars, and what have you. However, this headphones shines equally well with music of a far more elevated stature. When listening to bands such as MONO and Godspeed You! Black Emperor, the totality of emotion, warmth, frigidity, and emptiness is conveyed extremely well. I would describe this headphone as musical, yet accurate; lively, yet controlled. For this price point, it is probably the most refined thing you can find (or 'one of'). I've heard people describe Audeze's midrange as 'lush', but I loathe to use that word because it seems inaccurate. What else can I call it? Something fairly close, I think. Resounding? Beautiful? Something along those lines. It's not overly silky or smooth, and has what I consider an excellent tonal balance. That is, more specifically, the balance between the upper and lower harmonics seems very evenly distributed, with a nod towards the bottom half. And back to the bass, because I'm too lazy to edit: the way the bass crashes and falls is like the rocky beach of any northern coast - smooth, heavy, organic. Listening to Cult of Luna's The Beyond is simply a pleasure in-and-of-itself now, and gone are the days where listening to metal seems more often a chore than a quest for rapture.
Still, nothing is without its faults - save for Spinoza's conceptualization of God, I suppose - and the HE-400 suffers from several of them. First and foremost, I would say the comfort on these things is really quite mediocre. That's it; what more is there to be said? The headband is too narrow (this looks rectified for the newer, HE-400i model!), the clamping force is a tad too high, the weight is extremely substantial, and the ear pads could use an upgrade to a softer, more luxurious material. And I say this as someone who lives and breathes full-contact martial arts training on a near-daily basis; neck strengthening is a rather large part of my routine. Even with my developed neck muscles, I do feel fatigue after a good 2-3 hours on this baby. I can feel it even as I type - think I just finished my fourth hour, actually, and both my years and my head/neck will need temporary relief from what is such a marvelous burden. Besides its physical flaws, this HiFiMan offering also is a tad troublesome come the treble section. It's not bad, but it's not great. Good? Mediocre? Average? Perhaps a touch above average, but I hear just a touch too much sibilance and that ever-so-annoying raspiness/sharpness of metal-on-metal action so common when it comes to the higher frequencies of a drum set. If not for this problem, I would mark the audio quality as a perfect 10/10. For this, one point down. "Leash" in the Cult of Luna album aforementioned particularly highlights this dislike of mine.
Well, this is it! I can't really be bothered to continue, at least not now. These are my general impressions, and in no way, shape, or form do I claim they are objectively verifiable. Maybe if we can share sonic qualia one day? Until then...