HiFiMAN HE-400

EDIT:  My opinions and views on this set of cans has changed a fair bit after more extensive listening.  Please see the link below for my updated opinions on these headphones.
http://www.head-fi.org/t/755367/shootout-entry-to-mid-range-full-size-cans-feat-ath-m50-hd-558-and-he-400
 
My Story
First of all - WOW.  This is my first set of proper Hi-fi/Mid-fi cans.  It's also easily the best sounding anything I've ever had the pleasure of listening to.  However, since I'm new to the head-fi game, take this with a grain of salt. 
 
So where do I begin with these headphones?  I guess I should give some background on my listening history.  I wouldn't quite consider myself poor, but I'm definitely far from affluent.  This means that my listening experience has been severely limited.  Until I purchased the HE-400's, the nicest cans I've had the chance to listen to were a pair of my friend's ATH-M50's.  While quite nice, they didn't particularly blow me away.  The nicest pair of headphones I've personally owned were a pair of Sony MDR-MA 300's.  They're semi-open, have a LOT of fairly clean bass, recessed mids like you wouldn't believe, and decent highs considering the $50 MSRP.  I definitely got used to the very dark sound signature of those Sony's.
 
When I put the HE-400's on for the first time, I was immediately very concerned that I might have wasted $300 of my hard earned dollars.  They were a WORLD of difference from those Sony's, and I just didn't care for the sound signature out of the gate.  However, I decided to stick with them for a week or so and see if my opinion on the topic would change.  That was without a doubt one of the single greatest decisions I've ever made.
 
Although it took a while for it to sink in, I had a eureka moment a few nights ago as I was laying in bed, listening to a new album I'd been recommended (Dead Horse by Charts and Maps for anyone interested in a fantastic, FREE Jazz Fusion/Math Rock album).  While listening to the second track, I finally realized just what I'd been missing in all my music.  The mids were so clear and smooth.  The instrument separation was unparalleled to anything I'd ever heard.  The drums sounded realistic.  And then there was that saxophone.  It sounded like it was right in front of me.  I've never had such a positive visceral reaction to music before.  I found myself smiling uncontrollably (as an aside, I'm listening to the same album while writing this review and can't help myself from grinning like a madman).  I was hooked. 
 
I've listened to more music in the past few days than I have in quite a long time, and I'm finding it hard to stop.  If you're new to the world of headphones and any of this sounds like it might be up your alley, I highly recommend you just bite the bullet and cough up the $300 (while the sale lasts).  While I can't guarantee that you'll love them, the potential is definitely high with these cans.
 
Now, for the more technical stuff.
 
Build Quality
Overall, there's not a whole lot to complain about with the build quality.  The only real issue I've faced is this cable.  I hate it.  It's thick, it's stiff, and when I go to lay down in my bed, sometimes the audio will just cut out.  Others have pointed out this issue, and I've never had this problem with other phones, so I know the cable is to blame.  I'm also not a huge fan of the connectors, but at least I can live with those.  I'm definitely going to replace the cable soon.  If anyone has recommendations on an inexpensive set of aftermarket cables (preferably under 100 USD), please, PLEASE shoot me a PM. 
 
It should also be noted that these are HEAVY CANS.  They weigh in at nearly 1 lb.  The flip side to this is that they also feel quite sturdy. 
 
Headband could also use a bit more padding, but that's part of the next segment.
 
Comfort
Overall, they're pretty good.  I would prefer some extra padding on the headband (which I'll definitely be adding to these).  I don't have any problems with the stock cushions, other than a TINY bit of sweating, but I may try out the velour pads just for the hell of it. 
 
Drivability
I read one review where someone said his amp (I believe it was a Schiit Magni?) was having trouble driving these headphones.  My experience is the exact opposite.  I can drive these perfectly well from my ipod nano, and my stock gain (2.5x / 6x) O2/ODAC combo can absolutely CRANK these things.  On low gain I never have to turn the knob past maybe 20% of it's travel.  I shudder to think of the damage I could do to my hearing with these cans cranked on the high gain mode.  Since these cans have an impedance of ~50 ohms, pretty much any source with under 5 ohms of output impedance should have no issues with damping. 
 
Sound Quality
I've pretty much covered it all in my story above, but I'll reiterate here in case some of you skipped it.
- MIND MELTING MIDS
- Clear, present bass with a bit of a punch.  Wouldn't call this a bass-heavy can by any means, but it's certainly not lacking in quantity or quality. (EDIT:  After further listening on some of my favorite albums (that I feel also happen to be poorly mastered (see most The Fall of Troy albums) I've found that the HE-400's bass response just isn't up to par in terms of presence.  My previous pair of cans did just fine with TFOT, and you could actually hear Tim's bass through the mix, but with the HE-400's I have to use a fair bit of EQ to get it to shine through at HALF the volume of my old pair.  Bit more presence would be appreciated, but the clarity is definitely a stellar upgrade.)
- Fantastic treble.  While others have most definitely complained about treble issues with these cans, I can't say that I've experienced the same.  Your mileage may vary, but that's my two cents.
- The best clarity and instrument separation of anything I've ever had the chance to listen to (bear in mind that I am EXTREMELY new to this, so my experience is very limited.)
 

Conclusion
For my first entry into the world of Hi-Fi, I think I've made an excellent choice.  Although I didn't care for them out of the gate, I think these cans may very well be the best investment I've ever made (aside from my gaming rig.  It's pretty much my child.)  I may just save myself the time, money and trouble and just call this my end game, but at the same time it's making me wonder what lies just beyond the horizon.  Wish me luck on this crazy adventure that we call audiophilia, and don't forget to enjoy the music!

Recently i received a new set of HE-400s and took them for a spin.
I never made it past the first lap, so its time for the review.
I found their sound to be a combination of overly flat mids and spiky distant trebles awash in a sea of syrupy bloated
bass response with a touch of darkness throne in to hide any hint of presence or clarity.
I use a Woo Audio Fireflies and a ResonEssence Concero HP and a Maxxed out version of the discontinued Headroom Max as my sources, so, im not under-powering the HE-400s.
If you prefer overly flat mids and thick bass, then these are your best buy.
On a positive note, as i define the HE-400s sound as bassy with muddy mids, , they can also be described
as lush, rich, incredibly thick and wide, and very very warm......like a bear hug of low mids around your ears.
Sound-stage is impressive.
One thing is for certain, after you use the HE-400s for a while then change to any other headphones you own, your other headphones will ALL sound smaller.
Much smaller.
So, consider that as the other impressive caveat that the HE-400s can truly offer you along with the very nice sound-staging.
Do they sound bad?......No, not at all.......they just sound thick, flat, and wide.
Another way to think of their sound is if tubes in a headphone amp are very old and worn out and soft sounding..., that would be a way of describing the sound of the HE-400s...... very soft, very smooth, very round, very old analog.
You keep thinking, "wow, these could be so great if i could just add some upper mids and some treble".
And somehow the HE-400s are able to make their flatish - thickish- soft and round type of EQ tonality work, ,,,but that does not mean you have to like it.
I suspect that as these phones need power to make them speak, that many of the reviews you read whereby they are described as "bright" or "shrill" can be explained by the user trying to power these with an Iphone or some similar type device
which is starving the HE-400s and in that state they are going to sound brittle, especially at the top end.
However, if you give them the power they need and crave so that they can produce as they should, then you are will discover that they sound quite buttery smooth and very warm and thick and dark.
I like them, and i appreciate their sound, but my particular need is for more clarity in the mids and upper mids so that the music does not sound laid back and creamy smooth.
The HE-400s are nice cans, and worth the money, but be certain you are looking for their sound, which is nothing at all like a set of good dynamic open back headphones like the wonderful Sony MDR -MA900s.

First things first, there is a simple trick that solves all the complaints about the cable connectors - simply rotate each 720 degrees counterclockwise to build up some torque before you screw each one on clockwise.  Since you only need to screw 540 degrees clockwise to fasten them, the extra twist remaining in the cable keeps them securely fastened without having to overtighten.
 
The build is nothing special.  Yes the R/L markings rub off.  Also the screw placement is oddly asymmetrical.  Materials are not luxurious, and comfort is just average (though comfortable enough that I can enjoy them for hours on end without distraction).  They are somewhat heavy.
 
Bass is incredible.  In this price range, I am unaware of any headphones with this kind of bass extension, impact, and natural sound.
 
High mids are a bit recessed (less so with the velour pads), yet the mids as a whole remain clear, detailed, and vocals show great depth.
 
Speed, transparency, imaging: all strong suits.
 
These headphones absolutely shine with jazz, rap, electronic, funk, rock, and pop.

The review is based on the stock pads, not based on the upgraded velour pads.
The only problem with the sound quality is a weird color in the upper mids, around vocal range.  This is due to the stock pads that come with the headphones and must be replaced or modded.
They sound fantastic other than that but they just are not comfortable if you're not used to planars.
I expect these will grow on me, especially when I get the pads replaced.
 
Update:
Since modding and swapping pads on these headphones I must say it unlocked the true potential for these headphones.  Jergpad mod or velour pads will significantly improve their sound.

My source is a 2011 Macbook Pro-->Emotiva XDA-1-->Schiit Asgard-->HE-400
 
*Disclaimer* I have Jerpad 2.0 modded the headphones
 
The HE-400 does many things well, but the star of its presentation is the bass quality.  
It has very good slam for an open can, but its texturing is to die for! 
Cello sounds very realistic, with a roundness imparted by its bass extension.
 
In terms of the mids, male vocals have a very visceral, tactile quality about them, whereas female vocals seem to be missing a little bit.
 
The treble is rather hit or miss.  It seems to be fairly well extended, but it has a bit of tinny-nes and definitely sibilance that creep in from time to time.
I find electronic, rock, and vocal tracks to be the best for this, but then again I don't listen to many other things, so take this with a grain of salt.
 
To compare this with the HD800, which I have only heard twice in Bay Bloor Radio, the bass has better texture, but the mids are more "accurate" sounding on the HD800.
Of course, the soundstage/imaging on the HD800 trounces the HE-400, and the treble is far better extended on the HD800.
This is only from what I remember, and I believe the Sennheiser was hooked up to a Bryston amplifier.
 
All-in-all, I love the HE-400 for what it does best, just wish there was a bit more presence in the upper mids to make them a little flatter.

Review: HiFiMan HE-400 (revision 4)
 
published on October 14, 2013
 

(click for larger pic)
 
- download a printable 4-page PDF version of this review (target goes to a location on my Dropbox)

Intro

I originally got interested in the HiFiMan HE-400 due to early positive impressions by other Head-Fiers and eventually bought my own pair in November 2012, new from HeadAmp. This review contains my thoughts on the headphones, which I owned up until August 2013. Caveat: for various reasons I didn't listen to these headphones that much while I owned them and used them only for about 65-80 hours. I don't personally believe that planar magnetic headphones burn in either, which is another reason that the headphones never got many hours on them.

Equipment Setup

- Source components: Plinius CD-101 (CD player) (Signal Cable Silver Reference power cord, directly into wall), desktop PC w/ headphone jack on Yamaha YSTMS50 speakers
- Analog interconnects: Emotiva X-Series RCA
- Headphone amplifiers: Burson Soloist, HeadAmp GS-X MK2, Schiit Magni
- Headphones: Audio-Technica ATH-AD2000, MrSpeakers Mad Dog 3.2, Fostex TH900
 
The HE-400 (revision 4) was used only with the velour earpads, not the stock pleather ones.

Evaluation Music

- Alison Krauss & Union Station - Paper Airplane
- Andrea Parker - Kiss My Arp
- Goldfrapp - Black Cherry
- Helloween - 7 Sinners
- Infected Mushroom - Vicious Delicious
- Julia Fischer - Bach Concertos
- Machine Head - Through The Ashes of Empires
- Massive Attack - Mezzanine
- Megadeth - Countdown To Extinction [MFSL]
- Orbital - Snivilisation
- Ruth Moody - The Garden
- The Crystal Method - Vegas [2007 Deluxe Edition], Tweekend
- The Prodigy - The Fat of the Land
- Trifonic - Emergence
 
Negative Aspects
 
The flaws listed below collectively soured my experience with the headphones:
 
- Comfort & fit: The HE-400 was very uncomfortable on my head mostly because of the headband, which wasn't padded at all and frequently left the top of my head sore. I also never got a full "seal" with the ear cups due to the size and shape of the frame—i.e., the headphones were just slightly too big for my head at the smallest slide setting and didn't "clamp" enough to my head either, leaving slight open space. That may in part explain some of why I heard what I did with the HE-400, and it's admittedly possible that my fit issues could very well have been the source of my negative experience with the headphones.
 
- Cable quality & appearance mis-marketing: The HE-400's cable was one of the worst things about it to me. For one, the screw-in connectors were an annoyance to deal with (primarily because they were too small to easily turn) and always left me wary that they might break as well. In fact, I did break one of them from over-torquing and had to get a replacement cable through HeadAmp. Second, I thought the 3.5mm mini plug at the other end was a major error too for two reasons: (1) 3.5mm mini plugs usually indicate that a headphone can be driven well by portable & computer sources. I found this to not be the case at all with the HE-400. On my computer it required extra-high volume to sound loud. And on my amps it required high gain (where configurable) + high volume adjustment to sound loud. (2) I occasionally experienced sound drop-outs when I used the cable with a 3.5mm-1/4" adapter and frequently had to "shake" the adapter's connection to the headphone amp in order to regain sound. This occurred with all 3 amps, so it wasn't limited to a single amp. The problem was clearly with the cable's 3.5mm mini plug, as I've never experienced the issue with any other 3.5mm-terminated headphones.
 
- Overall lack of mid-range: I put the HE-400 through every major music genre that I listen to (classical, bluegrass/folk, metal, electronica/trip-hop) and had a hard time appreciating it for most of them simply because I found the mid-range overall to be too recessed, which negatively affected my enjoyment. It was just way too thin-sounding and never presented instruments like bass guitars or other elements like male & female vocals as properly full-bodied. It severely detracted from atmospherics/ambience as well—on music that was atmospherically dark, like trip-hop and certain types of metal, the stylistic "darkness" that should've been there was missing with the HE-400. I don't mean sonic darkness, I mean that kind of heavy, creepy, menacing quality that some tracks can have (for example, Massive Attack's "Inertia Creeps"). And the HE-400 tended to shove key musical layers to the background, like drums/percussion. In that aspect it was like the sonic inverse of the Audio-Technica AD2000/AD2000X, which both bring percussion to the extreme foreground.
 
- Boring bass: You'd think just having a lot of bass on a headphone would make it fun-sounding, right? Wrong. It depends on how it sounds, and the HE-400 had one of the most boring bass responses that I've ever heard. It reminded me of the "oonce oonce" bass in dance clubs—completely generic and indistinct with absolutely no real energy to speak of. Ok, the HE-400 had a lot of bass quantity. But the quality of that bass was just non-exciting, as it was just the equivalent of a generic-sounding bass "drop". There was just no impact, or force, or anything that sounded like the bass had some type of forward motion and wanted to keep pace with the rest of the music. And there was no tightness to it either, it was just a generic-sounding plodgy and ploppy blob. In fact, if there's one word that could sum up the bass for me, it'd be "ploppy".
 
- Spiked & unrefined treble: Ok, a lot of headphones have unpleasantly spiked treble. The HE-400 was just another case of that to me, and I like treble too! I'm a fan of the treble in the Sony Qualia 010 and Sennheiser HD800 for example. But the HE-400 had just too much zing and sibilance that made my ears wince on too many occasions. And it was unable to stay clean at high volumes, on music that was especially treble-heavy—i.e., it tended to blur ambient electronica at points where the music got increasingly complex & trebly.
 
- Over-diffusion: I'm generally not a fan of headphones that diffuse/separate the sound a lot, especially when it's obviously unnatural to the recording. (Case in point: HD800.) The HE-400 overdid this as well IMO and completely lost a sense of cohesion—it split apart bands way too much so they didn't sound like they were playing in the same room, for example. I'm pretty sure that most metal bands don't intend for their music to sound overly diffuse/separated and this aspect of the HE-400 especially annoyed me when listening to metal.
 
Positives?
 
Normally I'd try to balance a negative review with some positive aspects but unfortunately my experience with the HE-400 really turned me off to it, way more than any other headphones in recent memory. So I apologize if I can't come up with anything especially positive to say about it. I guess the best thing that I can say about the HE-400 is that it was technically competent—i.e., it had treble and bass, a fast impulse response, etc, but for me it strayed so far from the point of conveying music that it ended up registering as below-average in my personal rankings. Additionally, by the time I really started putting the HE-400 through its paces for this review, I also had the MrSpeakers Mad Dog 3.2, which I'd be inclined to say is the superior-sounding planar magnetic headphone for less money.
 
As far as amping went, I used mostly the Burson Soloist and HeadAmp GS-X MK2, and only minorly the Schiit Magni. The Magni was able to drive the HE-400 effectively but that's about all it did—the HE-400 really didn't sound that great on it, especially compared to the Burson Soloist. The Magni was also unable to drive the HE-400 at ultra-loud, non-earsafe volumes without causing audible distortion in the bass frequencies (on extra-low/powerful bass notes). And although the Soloist and GS-X MK2 were better-sounding amps, neither of them helped to rectify my issues with the HE-400. The GS-X MK2 in particular only amplified its sonic flaws.
 
Addendum - Review Notes
 
My review notes are included here in their own section for convenience. These provide specific detailed info not included in the review. Notes start below the asterisks.
 
***
Terrible cable quality at both ends (screw connectors too small to easily handle, connectivity issue when mini-plug used with 1/4" adapter). 3.5mm plug mis-leading, HE-400 nowhere remotely efficient enough for use with portable sources. (Needs High gain to achieve sufficient volume on Soloist and GS-X at moderate settings.)
 
Overall passive, laid-back sound, in a V-type signature, with very emphasized treble and bass.
 
Julia Fischer - Bach Concertos

1. Strings clear & "shimmering", not too unlike HD800, but also diverges instrument sections widely. Very separated sound, not very cohesive. Almost too much channel separation. Treble overall reminiscent of HD800—has similar issue as HD800, causing wispy/glossy-sounding violins. Lacks subtle musical details that the OII would have (inflection, dynamics, bowing technique, etc). Lack of overall mid-range content negatively affects both violins & harpsichord.

 
Massive Attack - Mezzanine - "Teardrop", "Inertia Creeps"

1. HE-400 fails to portray analog-like warmth of Teardrop that should be there. Tape hiss doesn't add atmospherics either and is just “there” as background noise. Kick drum not very obvious as a kick drum either, also lacks distinction. Lacks percussive-hit drive into belly drums of Inertia Creeps as well. Drums sound slow and lack the fast vibration decay as heard on OII/BHSE. Dark atmospherics & ominous sound of track totally not conveyed by HE-400 either. 3D's vocals also lack a heavy intonation.

 
The Prodigy - The Fat of the Land
Infected Mushroom - Vicious Delicious - "Becoming Insane", "Vicious Delicious", "Change The Formality"

1. Bass on HE-400 is low but also sounds very boring. Has quantity, but lacks "motion" and power—i.e., drive/punch/impact. Not tight either and is semi-plodgy. Sort of blobby & ploppy. Almost excessively ploppy depending on music.

 
Helloween - 7 Sinners - "Who is Mr. Madman?"

1. This recording especially shows faults of HE-400—drumming is barely noticeable on it. Shoved too much to background and doesn't sound like an integral part of the music. Polar opposite of something like AD2K which brings drums to extreme foreground. Bass guitars also completely lack fullness. Track completely lacks excitement of AD2K.
2. For metal music specifically, HE-400's frequency balance skews more towards guitar string plucks/vibrations. Huge lack of general bass fill to bass guitars and vocals that more often than not offsets the intended atmosphere, so most tracks don't have an appropriate "metal" sound.

 
Porcupine Tree - In Absentia - "Blackest Eyes", "Lips of Ashes"

1. HE-400 lacks heavy/full sound that would add more to music. Guitars stick out too much in mix. Bass guitars detracted too much. Separated, diffuse sound lacks cohesion. Opposite of Grado-like where the band is close together and upfront. HE-400 splits the band too far apart. Treble is the aggressive element on HE-400, not the band's bass guitar as it probably should be.

 
Beyond Twilight - Section X - "The Path of Darkness"

1. HE-400 shoves male vocals to background too much and recesses them too much as well. Lacks heavy, dark sound on HE-400 that should be there.
2. Not sure HE-400 would be ideal for black or tech metal due to lack of mid-bass & mid-range (male vocals too recessed, bass guitars detracted from too much as well).

Not perfect but they do a lot of things very well, probably the best value headphones. Bass and midrange are excellent, treble is too bright and harsh but with EQ it sounds ok.

First of all, I was not running these from appropriate amplification at the time (Audigy 2 ZS Platinum Pro breakout box). Secondly, I have exchanged these for some other phones, and have only had them for a few days (also potential defects). Third, I am relatively new to the hifi scene. Therefore I have deemed it fair to give them 3.5 stars in order to not ruin the average. I felt I had to after that guy gave 1/5 stars for some reason.
 
With that out of the way, onto the review.
 
EDIT: Please ignore the scales to the left, they do not reflect what I think. I can't change them for some reason.
 
Audio path:
FLAC 44.1 16-bit or MP3 V0/320, various genres -> JRiver Media Center -> ASIO -> Audigy 2 ZS -> Platinum Pro breakout box -> HE-400
 
Previous phones i've owned are the Sennheiser HD202 (broken, piece of crap) and HD555's with the foam mod. I had the former for about a year and the latter for 3 or so.
 
Design / Build

1. These are Revision 2's.
2. Personally, I think these look fantastic. They are how I would design headphones if given the opportunity. It reminds me of something like a sleek old muscle car with a modern facelift. The colour may look showy to some in photos, but in real life it's not quite the case. It's a nice, dark shade of indigo blue that doesn't look gaudy at all. In fact, they look much more attractive and unique than the HE-500's with its boring grey scheme.
3. The housing appears to be some cheapish plastic, unfortunately. The paint job seems decent though.
4. The mesh can be removed fairly easily by pulling out a plastic retaining ring with your fingernails. This adds some nice modding options (diamond/criss-cross grills anyone?) that can potentially affect the sound. You could probably paint the ring to give the phones some accents too.

1. Apparently both drivers are wired in reverse polarity (I couldn't confirm this because I didn't have a mic). A few people argue that it has a negative effect though I can't say for certain.
2. Cable is removable, though uses unusual mini coax connectors for the drivers. I guess they used them instead of mini XLR for cost reasons.
3. Stock cable is not horrible as everyone makes it out to be (coming from HD555's, anyway). Bit too long and stiff though.
4. I feel that the connectors detract from the aesthethics (and function) however, and they should simply be sticking straight out the bottom of the housing; instead of being recessed (makes it more difficult to screw on the cables as well).
5. Earpads are a bit fiddly to put on, and they spin freely (not a big deal).
6. The round things with Hifiman logos that hold the arms for the housings seem to do a decent job of retaining its position.
7. On a whole, these don't feel or look like cheap headphones. They seem like they would take much more of a beating than the dynamics i've owned, and I don't see anything that would crack in everyday use (unlike the HD202 and HD555's). Not sure how they would cope being dropped onto a hard floor from waist height however.

 
Comfort / Fit

1. Repeating the words of everyone else, they are heavy. But when I first took them out of the box, they weren't as heavy as I thought they'd be.
2. Weight only posed a problem in regards to pressure on the top of my skull. It was probably the most annoying thing comfort-wise about these. I never experienced any kind of neck pain.
3. Headband padding is some faux leather and way too thin for my liking, especially with the weight of these. It was somewhat more bearable when I ripped the pleather padding off my dead HD202's and stuck them on though
   
4. Included earpads (pleather) are not as soft as i'd like and made my ears hot fairly quickly. The optional Hifiman velour pads were actually stiffer than the pleather ones (???) and definitely not up to scratch to my HD555's stock earpads, but at least my ears didn't get too hot. Overall, they did improve the comfort noticeably though (and sounded a bit better too).
5. It's possible to mount earcups from other manufacturers on. I've seen people mount Lawton Audio slanted leather cups and they look awesome.
6. You can bend the headband to fit your head better (manual says so), though I felt no need to do so.
7. All in all, actually not as uncomfortable as some people make it out to be. But I am constantly reminded of its presence, which detracts from the listening experience sometimes.

 
Sound

1. This is probably the part of the review I feel the most uncomfortable with as a budding headphone enthusiast. Bear with me. Also note that they probably weren't amped properly.
2. I was excited, so when I first got these I soon plugged them into the only source I had my hands on at the time: Galaxy S II (with varying genres of FLAC files running through PowerAmp player). I did not expect anything amazing at all. And I got exactly that. Nothing to speak of. I could only just barely get them loud enough at max volume. To be expected of a phone, even though HiFiMAN says it's good enough for portable devices.
3. I immediately plugged them into my Audigy 2 upon arriving home and started playing my favourite track: Give Life Back To Music by Daft Punk. I wasn't blown away, though I wasn't really expecting to be. I wasn't blown away when I went from my HD202's to HD555's either though.
4. I then started to play some ambient music (stuff like Jonn Serrie, Steve Roach) because I wanted an idea of how immersive it could be. Wasn't blown away here either, but I noticed the soundstage seemed noticeably wider than my 555's, though the depth was about the same I think.
5. Deadmau5 - I Remember - to test the bass impact and vocals. First of all, I am not a basshead. I was actually quite surprised here. When I heard the pulsating bass, it was strange, but not in a bad way at all. It sounded very much like a subwoofer, yet I felt no rumbling at my feet. I actually went to check if I accidentally turned my 2.1 set on. Still, they could have used a touch more bass quantity, though amping them properly probably would have done the trick. As for the vocals, they seemed less than impressive to me. They didn't really stand out and sounded a bit hollow to my ears.
6. I enjoy some classical here and there. Played some woodwind stuff. Problem: Certain notes were quite uncomfortable to listen to, I blame the treble spike.
7. I tested the bass further by doing some frequency sweeps within 20-200hz. The bass extension was truly something to behold. It really was like having a subwoofer mounted to your head (minus the physical rumbling).
8. Throughout all that, I experimented with various angles and distances between the drivers and my ears. A couple of things to note: there was significantly more bass quantity when I held them about 2cm away from my ears. Slanting them inwards (like on the Audeze LCD-2) seemed to reduce the 'nasal' tone significantly and make them sound more speaker-like. In short, they are quite sensitive to positioning compared to most dynamic phones.
9. Played some games, namely Mirror's Edge and Battlefield 3. Things like gunshots and explosions sounded lacking and hollow compared to my 555's, also I didn't feel as if anything took advantage of the bass extension. Then I wondered why the sound positioning didn't seem as good as the Sennheisers. Sounds coming from the front did not sound like they were quite in the center for some reason. I concluded that they weren't suitable for this purpose and I simply went back to my 555's for gaming.
10. Watched some video reviews on YouTube for a bit. Voices didn't sound right. I then swapped over to the 555's. It sounded like it was in the center as it should. I was confused. Played some movies to triple check. Same problem. I was worried. I posted about it on Reddit, someone believed it was a driver mismatch issue.

1. At this point I noticed my ears were tired and ringing more than usual (already had tinnitus). I didn't have them much louder than I usually have the 555's yet it fatigued my ears far more for some reason.
2. I'm not sure what to think of burn in yet, but I left them burning in on my desk in a cardboard box at slightly higher than normal listening level for about half a day. No idea if it made a difference soundwise. But during the time I felt that familiar fatigue in my ears. I feel there's some kind of resonance or something that I can't put my finger on, causing strain to my ears. This was probably the biggest problem I had with these, with the sound positioning issue following very closely behind.

 
Conclusion
I really wanted to enjoy these. They are aesthetically pleasing and I was very excited about diving into the world of planar magnetics. Unfortunately, quality control issues and a bizarre fatigue problem ultimately stopped me from enjoying them. That aside, and truth to be told - most of what is going to be coming out of headphones for me isn't music, as much as I am very enthusiastic about the stuff. I want general purpose headphones for computer/entertainment use that is decent at everything - music, gaming, TV shows and film.
 
I think I would have kept these if I had a dedicated listening setup for music. Heck, I don't even have a headphone amp yet. I have since replaced them with DT880's (Premium 600ohms, yes I need an amp, just trying to be future-proof here). I think they are a step up from the HD555's in every way for what I use them for. However, I do miss the HE-400's in a lot of ways. They provided a speaker-like experience. They sounded full and allowed you to feel the music, and just had this charm about them I can't put into words.
 
Would I recommend these headphones still? Yes. These issues might not even bother you at all.
It almost ticks all the boxes, but just misses a couple of critical ones for me.
I eagerly await a successor so I can give HiFiMAN another fair go.
 
I hope this review, though somewhat unrefined, helps people.

 
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Disclaimer: A big thank you to Electromod for loaning me the HE-400.
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For those of you who don't already know - Hifiman are a Chinese company, although technically founded in New York (2006), their R&D department is in China. In just a few years they've made quite a name for themselves making high end portable audio players, amplifiers and headphones. For the latter their focus has been with 'planar magnetic' (commonly and less correctly referred to as orthodynamic, or 'ortho'), apart from their entry level model, which costs £300. The ortho's range in price from £400 to £1000, but share a very similar design - essentially only the colour changes. Their model numbers can be a little confusing too, so let me try to get my head around this hierarchy:[/size]
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Their current flagship model is the HE-6. This now has a baby brother with the HE-4, but originally the next model down was the HE-5 and that was replaced by the HE-5LE. Both of the HE-5 models have now been phased out and replaced by the HE-500. Finally there's the focus for this review - the HE-400, which is the company's cheapest and most successful selling ortho to date. [/size]
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Hifiman have made a couple of other interesting products recently too. Like the EF-6, a high-end headphone amplifier that partners with the power hungry HE-6 headphone. Then there's the EF-2a, an affordable ($169 US) USB DAC and tube amplifier. More recently Hifiman have been branching out into in-ear monitors, with the RE-400. Let's not forget about their portable audio players too. Models like the HM-801 and the more reasonably priced HM-602, I've always been interested by these, but unfortunately never got the chance to try them. So they clearly have the audio pedigree, albeit a pretty short one. [/size]
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I've tested a lot of open back headphones lately, with the DT880, HP200, GMP400. Plus although I haven't reviewed them, I've spent quite a bit of time with the Sennheiser HD600 & HD650 too, so let's see what I think of this more expensive newcomer.[/size]
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     SOUND[/size]
[size=medium] The HE-400's sound is well balanced, but it's also very impressive and exciting. The real icing on the cake for me is their versatility with various genres. It's an airy and clear sound with slightly warm leanings. There's lots of presence and body here, but with very little colouration or fatigue. Bass almost verges on the epic considering it's control. Mid-range is clear and detailed, while the upper ranges sparkle without being harsh. The soundstage is wonderfully spacious and three dimensional, as is instrument separation. [/size]
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That pretty much sums up the HE-400 for me, it's a stunningly likable headphone. There really isn't much to complain about in the sound department, even at this price. If the Sennheiser HD600 was a little cheaper I would say they are equally matched for value, but this is purely based on sound. I have a couple of reservations about the HE-400's comfort, but also at the HD600's price point I would still give the overall crown to the Hifiman. Damn it! Now I'm getting into comparisons, OK I'm struggling to say more here so I will move on and go into more detail later on...[/size]
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     AMPLIFICATION[/size]
[size=medium] Running the HE400 from my phone (Galaxy Note 2) and trying to get the sound loud proved a bit of an issue. At maximum setting it was about 90% of the volume I wanted for Electronic music, which means it would be about 70% for most classical music. That's unfortunate because the sound quality wasn't too bad, but let's face it, if you're looking at these headphones you will most likely already have some decent amplification for them. [/size]
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Proper amplification wise I started with the Schiit Modi and Magni, which have a tremendously compelling performance that combines very well with the HE-400. I can see why Electromod concentrate on these two brands almost exclusively, you can't go too far wrong with them. The only down side is that the three entry level models will set you back around £600, which is a lot to swallow in a single purchase for many people. Perhaps it's slightly over the sweet spot of diminishing returns too, but wow does it attain a seriously compelling sound![/size]
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Next up I partnered the HE400s with a nice portable solution for laptop use with the Ifi iDAC (combined DAC/amp that I will be reviewing soon), which is rather unusually is capable of 24bit 192khz through USB and is purely powered by the USB bus. The only other unit I had like this was the iBasso D7, which I also tried with the HE-400. The D7 Sidewinder was actually a lot better than I remember, possibly because it's better suited to more demanding headphones like this. Anyway, it still exhibited it's typical power issues when plugged into the non-powered USB ports of my laptop *sigh*. The Ifi iCAN showed no such power issues and drove the HE-400s loud and well, no matter what ports I connected it to. This was not as a compelling sound as the Schiit combo, but don't forget this is a lot more convenient if you're away with a laptop, or perhaps a Windows surface?[/size]
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I also plugged the HE-400s into the Benchmark DAC2 HGC. This combined DAC/amp might be ridiculously more expensive than the HE-400, which are not cheap already, but it was understandably entertaining. On the Fostex TH600 (also being reviewed soon), the DAC2 was almost surreal in it's separation, but the HE-400s soundstage stayed a little more reasonably great and retained a level of coherent realism as well. The imaging was still given a wide push compared to anything else I tested it with and it is lot of fun. I'm left feeling that you can safely spend considerably more on amplification with the HE-400s and keep getting tangible improvements, where that same investment could be a waste with other headphones.[/size]
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[size=medium]     MUSIC[/size]
[size=medium] Here are some individual music tracks and how I felt the HE-400s coped with them. Most tracks were listened to in CD format with lossless compression. All tracks are also available on Spotify, which on the 'premium' service are maximum quality MP3s and I find these highly acceptable.[/size]
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1. Jesper Kyd: "State Of Decay Main Theme" - I actually don't know what this is a score for, I just follow the Danish composer because I love some of his other game soundtracks.   One of reasons the HE-400 is so good with Classical and soundtracks is it's nicely flat response, although flat can sometimes mean a bit boring, it certainly doesn't here. There is a quality and emphasis to the bass and treble, while not being offensive and that really makes these headphones special!
2. Excision: "Deviance - Original Mix" - With the HE-400s superb upper bass body I had to try some nicely powerful Electronic / Dubstep type tracks. This one has some great & dynamic bass! The HE400s do a stunning job of rendering it without any mid-range contamination. This is one of those headphones that can be addictive for bass as well as agile and powerful, yet delicate for something like classical.
3. Jason Mraz: "I'm yours" - The bright and crisp vocals are beautifully presented, produce zero harshness and have a great sense of air. I want to say that these headphones make a compelling argument for vocals, but again it's their versatility that seems to really stand out.
4. Fear Factory: "Replica" - The HE400s transition from delicate vocals into aggressive death metal with ease. There's great attack and speed from the guitars, while aggressive vocals are clear and nicely separated as possible. This is as good as I've heard this music. 
5. Amy Winehouse: "Back To Black" - This track has nice sense of smoothness and good emphasis on vocal clarity. It's as entertaining with slow or simple music as it is with fast, densely packed instruments fighting for attention. 
6. Orishas: "A Lo Cubano" - This latin pop is extremely enjoyable through the HE400s. It's a nicely mixed, dynamic sound that will have you foot tapping at the very least and these headphones bring out the full soul of the music. 

[/size] [size=medium]      COMPETITION[/size]
[size=medium] Comparing these headphones to others can be rather difficult. There are clear differences and advantages to orthodynamic drivers and the problem with comparing the HE-400s to other orthos is that there's nothing else in quite the same price bracket. On the low end there's Fostex's most expensive orthodynamic headphone - the T50rp (£100). The best option here is to compare the HE-400s to a modified T50rp, like the Mr. Speakers 'Mad Dog', there are several others, but this is one that I've reviewed. At around £300 this is a much closer price to the HE-400 and luckily I still have them here to compare. The only other orthodynamic manufacturer around is Audeze, but their cheapest model is twice the price of the HE-400 and is a lot harder to find. This means that the next most expensive ortho after the HE-400 is HIfiman's own HE-500 (priced at £700), so you can see the problem. So for this reason I will open the comparisons up to some dynamic driver headphones as well.[/size]
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Mad Dog - This is the only other orthodynamic headphone that I've had the fortune to try so far. Although it's based on a much headphone costing 1/4 of the HE400, the external changes that Mr. Speakers have added to it (additional leather headband and new Alpha pads) make it feel infinitely more comfortable than the original, or indeed anything else around that price. In fact this is one of the nicest headphones I've worn and it clearly beats the much heavier HE400 in the comfort arena too. Apart from weight the big enemy of the HE400 is clamping force (which it probably needs to stay on your head), it's a little too tight. This is made worse by the ear-cushioning being rather hard, which being symmetrical doesn't hug the head nearly as nicely as the Mad Dog's 'Alpha' pads. So the HE400 doesn't seal quite as well, but being open-back it doesn't really need to and here we reach our next problem comparing the sound. The original Fostex T50rp was a semi-open headphone and it isolated reasonably well, but the Mad Dog modification has made it more like a closed-back. [/size]
[size=medium] The air and separation of the Mad Dog may not be quite as impressive as the HE400, but the soundstage is stunning with both. The tonality of the two presentations seem pretty similar, especially now that the Mad Dog is using the new Alpha pads, they're both a little on the warm side, but both manage a staggering lack of colouration into the mid-range, shine for vocals and have very well controlled upper ranges. Both headphones need nice, powerful amplification to flourish, but I would say that the HE400 comes out a bit ahead on pure versatility of sound quality (possibly more for Classical and Jazz) because of the few open-back qualities. If you find yourself sitting on the fence between these two headphones I would recommend mostly using the need of isolation to steer your decision.  [/size]
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Sennheiser HD650 - This is a classic, well balanced dynamic headphone and it's price is close to the HE-400 (£330 vs £400). Comfort wise the HD650 pretty much wins. Not only is it very light, but the ear-cushioning is fabric, which makes makes it a bit more comfortable and less hot. The HD650's clamping force is similar to the HE-400, a bit too much relative to weight, but since the weight isn't there it's less of an issue. Like the HE-400 the HD650 has dual entry removable cable, although the Sennheiser's push fit might be much easier to use it also seems more problematic under constant use. [/size]
[size=medium] So tonality wise the HE-400's sound seems to sit neatly between the Sennhseiser HD600 and the HD650. With the dynamics the more neutral HD600 seems to be what most audio enthusiasts & pros  prefer and I agree. The HE-400 is a little warmer than that, The upper bass has a substantial weight and kick to it, but it doesn't poison the mid-range as many lesser headphones do. By comparison, even the HD650 is a bit bloated for some music, although it's saved somewhat by being in the realms amplification tonality balancing, which is why I think it's loved so much. [/size]
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I wish I could say more about the Audeze range and how it compares here, but unfortunately I haven't had the chance to try them yet. Since the price is so far different from the HE-400 to the LCD-2 I'm too worried about this right now, if I get my hands on the HE-500 it will be more of an issue[/size]
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[size=medium]      BUILD[/size]
[size=medium] The HE400s are one of the most heavy headphones I've tried to date. This seems to be a theme with the orthodynamics from Hifiman and Audeze. In the Hifiman's defense there's a lot of heavy-duty metal in the construction. Actually the first bit of plastic you'll probably find is as you examine the cable terminals. Then there's the fake leather headband & ear cushions, but apart from maybe a couple of tiny washers (and perhaps the driver assembly itself) the rest is all metal. They feel very strong and the design is nicely simple, which at least seems like parts are easily replaceable. [/size]
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Speaking of removable & replaceable parts Hifiman have done a nice job with the cable. Yes, you expect a removable cable at this price (even if you don't always get one), but this screw fit, dual entry cable is a really nice touch. I guess if I was to nitpick I could say that it's a little fiddly to secure at times. A better grip on the screw mechanism and end of the cable, so you could hold both and twist more easily would be appreciated, but this really isn't that bad. The other end of the cable is terminated by a 3.5mm connector and it comes with a push on 6.35mm adapter. I would have preferred to see a 6.35mm connector here and an adapter for smaller jacks - a la Sennheiser HD650, again a very small nitpick. [/size]
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     COMFORT[/size]
[size=medium] The large space inside the ear-cushions makes for an almost perfect comfort for the ears themselves. The HE-400 might be described as a 'Lightweight' on the companies website, but it still weighs a hefty 440g. To better manage the pressure on the headband and stop the headphones from slipping down Hifiman have made the clamping force quite a bit above average and some people will find this annoying after a while. OK, it's not the most comfortable headphone in the world, but it's not that bad either. I wonder if a velour type ear-cup material could have softened the clamping pressure and lowered the ear temperature somewhat.[/size]
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     FINAL WORDS[/size]
[size=medium] OK, I have a couple of reservations about the HE-400s comfort, which I know I made sound worse than it really was, but overall there really isn't much to complain about with this headphone. I would still give comfort & fit an 8/10 score. [/size]
[size=medium] Overall I really love the HE-400 and I can't recommend it highly enough. If you can afford it and you like a generally balanced sound with impressive bass body then put them at the top of a small list. This is the cheapest high-end production orthodynamic headphone available at the moment, but it certainly doesn't seem like a cut-down model. It's also the cheapest one that I have tried, so I hope to try many more soon (stay tuned).[/size]
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If you can't stretch to this budget, but you like the idea of this sound then I highly recommend looking at the SoundMAGIC HP200. [/size]
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[size=medium]     EQUIPMENT USED[/size]
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[size=medium] Desktop PC, Dell Vosto Laptop, Samsung Galaxy Note 2, Audiolab M-DAC, Shonyun SH-306A, Schiit Modi & Magni, Epiphany Acoustics E-DAC, Benchmark DAC2 HGC, SoundMAGIC HP200, Beyerdynamic DT880 600 Ohm, AKG Q701, Sennheiser HD650, Sennheiser HD600, AKG Q701, Mad Dog (Fostex T50rp mod), Fostex TH600[/size]

Positives - clean extended, balanced bass. Lacks the physicality of an LCD-2, but that's not unexpected.
 
These are large, heavy headphones, that I found surprisingly comfortable to wear  when used with the velour pads. As reference, I have a small head, am not particularly sensitive to pressure on the top of my head, but am quite sensitive to pressure around the ear. For me, these were way more comfortable than I expected based on experience.
 
Build quality of the headphones seemed good - stock cable cover (not the cable itself)  was already separating at the Y junction however (purely cosmetic impact but not a good thing).
 
These headphones seem to be generally well regarded, but for me there was one factor that made them unusable - the treble. Fair disclosure - I am not a fan of overly bright treble, however with the HE-400 something beyond simple brightness was happening - almost a resonance effect in the highs. The impact for me was that listening to the HE-400s for extended periods made my ears hurt (beyond simple fatigue).
 
In some other posts, I have read about "tizzy treble" being tamed by carefully tightening the headphone cable connectors (which have a PITA design). This could have been my issue, but if it was it's certainly a design flaw. I could have had a bad unit, or my unit may have sounded as designed - I don't know. I do know that I could not listen to them for extended periods of time.
 
These were known good HE-400s without previously discussed (and now long corrected) build issues.

 
 
My take on these cans:

I've had the HE-400s for about year, and am now running them through a V-Dac II into a Burson soloist. 
Argon 5057 Cables between the amp and dac. My pair have the revision two casing (White-ish).

For modifications, I swapped pleathers for velours and removed the mesh that was glued onto the grills, no problems caused from that so far so thumbs up. It would probably be a safer bet to keep the hifimans under cover once in a while so they don't collect too much dust. These two mods are a must for anyone wanting to get the most out of these cans, however I wouldn't recommend the mesh mod if you have an already bright system as it slightly adds more treble and contributes to more fatigue (at least that's what I have observed). 

Genres I listen to: Metal of all kind, female vocals/acoustic, pop, dubstep & electronic. I can only comment on my own system because i've never owned anything else. The sound you get from these is very full, bass is perfect, prominent in the mix but not too much that it takes away from anything else, mids are really nice, gives guitar and vocals that extra richness. I have had to EQ the highs a tad, because these can get harsh with some less stelar recording mixes, Soundstage and imaging is good, you can pinpoint all the different elements in the song. One of the only negative things that I can find in the sound (and I may be over-emphasizing this) would be the really wide soundstage (more on the sides and less in the centre) that may make music that's played on a stage seem less realistic. This doesn't really bother me but if you're really looking for that speaker-like soundstage, other cans may do this better. This wide soundstage works perfect with more digital music like electronic etc.

The HE-400s build quality (driver casing/headband,etc) seems really durable, but these cans really need some refining. There are some things I feel could have been better, the 'Hifiman He-400's logo paint has started to fade, the R/L channels have completely dissapeared over and the cable has started to ware right before the connectors. Also, comfort is one of the big cons of this otherwise, really great sounding headphone, so take this into consideration (I am looking into upgrading to the revised models, HE-560).

What else can I say..I wouldn't say this headphone responds alot with better equipment, probably because of its efficiency. The V-Dac and Burson amp did make subtle changes but if you're budget is limited, going with less expensive options won't set you far away from the headphone's full potential. Only thing I would look into a headphone from this would be more detail, less brightness, more realistic imaging, and refinement in build and comfort.  I think synergy is pretty good, the Burson Soloist gives the HE-400's all the power it needs (does not need this much), and the Musical Fidelity Dac adds warmth so anyone looking at this setup, go for it. Conclusion: All rounder cans, great value and a nice step into the audiophile world. Feel free to message me about the headphones, dac or amp. and thanks for reading my review.

EDIT: Hifiman has released two new models, the HE-400i and the HE-560, these are discontinued.
 

Wow after not being active in head-fi for a couple of years and finally being back to be able to own a good headphone like the HE400 is such an honor.  I stop searching for awhile after owning the D2000 and now I wanted to find something to compliment the D2000, I decided to search.  I finally reached the HE400 and it reminded me what I love about this hobby and why I love headphones.  The HE400 is a headphone you can truly appreciate with smooth mids, nice black background, none offensive sound, open, comfortable, and look professional to boot!  I can't say more as everything can be found here in head-fi and to me word can't explain what these headphone can give.

Upon getting them the first thing I noticed was the build quality, its very good as you'd expect from HiFiMan and also how comfortable they are. I had other cheaper headphones but they weren't this comfortable, I can wear these for hours no problem at all.
 
As for the SQ its just great and I'm quite hard to please when it comes to SQ.  Three things I look for in a good IEM is detail, good mids and a good soundstage so I was hoping the HE-400 could stack up. Now with the soundstage I knew they would be good being open-backed and man are they, very wide with excellent depth and good height along with great imaging and good separation. Now the mids are the meat of music so they have to be good and the HE-400 while not as forward as I like they sound great, smooth and warm with good detail just how I like it. As for detail that was my biggest worry because coming from BA based IEM's like the SM3, e-Q5 and BA200 they all have very good detail and micro detail. The HE-400 really surprised me with the level of detail, now they don't quite have the micro detail of most good BA IEM's but they're not to far behind, I don't feel like I'm missing anything in the music. The bass and highs are also very good with the highs being a bit bright but not to bad over all and the bass on planars I've heard is very good and the HE-400 is no different with nice punch and very good depth and rumble but these aren't true basshead headphones though.
 
So over all I'm very happy with the HE-400 and honestly I haven't really been using my IEM's since I got these a little over a week ago. They have good detail and a great presentation so if your looking to get into good headphones unlike Beats or even Bose the HE-400 is a great place to start and I'm already looking into getting the HiFiMan HE-500 because planar magnetic is the way to go imo.

When I originally got into this hobby some 2 years ago, my first run of purchases included Sennheiser HD650's, Denon D5000 and Ultrasone Pro900's. I also had a couple beaters from Koss laying around like the Porta Pros (which I LIKE!). So upon purchasing my first true head amp (a Fiio E10) I thought my journey was over.... I had an amazing closed headphone, an amazing open headphone, a decent amp/dac... nuff said. Lets close the book on this consumer business and listen to some music.
 
From there I focused a good amount of my energy on (A) fixing up my 54 Lincoln and (B) mechanical watches..... I was in the throws of said watch obsession waiting for Steinhart to fill inventory on the Ocean 44 dive watch when I saw an episode of "How It's Made" on TV at the AKG factory in Austria where they take you through the steps of construction on one of the K702's.
 
Headphones!.... OH I LIKE THOSE
 
Since Steinhart was pushing their restock date back to August... maybe I can spend some of that money that is burning a hole in my pocket on a pair of Headphones.
 
And so the bug bit again.... But this time reading through forums, websites and reviews the kiss of death was bestowed on the K701 and 702 (which were my knee jerk target purchase after watching the show) but words like: lacking bass, thin sounding, airy and very NEUTRAL were intertwined into descriptions of their sound.... meh! I cannot handle thin sounding anything.
I've been to too many live shows to be able to pass off a thin sound as accurate.
 
Also (to me) the word "Neutral" conjures up images of a lifeless two dimensional sound that is lacking pace rhythm& and attack. Neutral is about as exciting as FLAT
I cannot imagine an OEM that would enjoy reading a review of their products, headphones, speakers or otherwise as "very flat and neutral".
 
So after jettisoning the 702 notion on its face, further Headfi forum reading of 'this vs that' impressions and product reviews and general chatter brought forth numerous mentions of a new player in the game... A company out of China called Hifiman who's entire line up of headphones consisted of planar magnetic drivers and open back designs. Even though the company hails from the PRC, they have a presence on US Soil that is comprised of a technical support staff and New York based distribution.The more I read about the Hifiman planar magnetic headphones, the more they starting working their way to the top of my list.
 
My pops raised me on a steady diet of vinyl with big power wars era receivers and massive floorstanding dynamic speakers but I remember spending time at my Uncle Johns in the summer where he had 2 big Magneplanar speakers set up in his game room. I don't remember a whole heck of a lot from back then but I do remember that I wanted my Uncles system.... So it became clearer and clearer to me that Hifiman was going to benefit from my next purchase. About the time I started my hunt, the HE400 model had been on the streets long enough to get through Rev 1.... and long enough for a couple of reviews to make it onto the street.
 
An article from Headfonia gave it a restrained thumbs up but Steve Guttenberg of CNet Audiophilliac fame gave it a gushing review. So as an impressionable young mark (er man) these last two votes of confidence were enough for me to pull the trigger. And so about 10 days after purchasing the headphones from Amazon for $399, they arrived at my doorstep. However upon taking delivery of the box there were obvious signs of having shipped direct from China and markings on the box gave me the impression they were shipped from a Chinese retail outlet as an in store demo. When I opened the box I was even more dismayed. There was no fancy case like had been shown in the literature and early reviews... Just a simple retail class cardboard box. I opened the box to find a pair of what looked to be a pair of blue HE400 but they were covered with a white dust and seemed to have been haphazardly packaged into the box.
 
"Is this some damn knock off or something?" was my original thought... 
 
The sticker on the exterior of the box seemed to imply that this was some demo model... yet I paid full price.... What!
 
Needless to say the Hifiman HE400 and I did not have a very good introduction... no love at first sight here.... I was on high alert once I saw that the package had made its way from China and because the way it was boxed with the headphone crookedly placed in the box, it did not seem to be packaged with the type of professional polish one would expect to find from a relatively high cost consumer product targeted for retail sales. I was therefore a bit miffed from the start. Then I plugged them in and pushed play and that is where all the hand wringing fell away.
 
Up until this point all of my headphones were on the warm and/or bass heavy side.... Denon D5K's, Ultrasone Pro900's, Porta Pro's and Klipsch Image Ones that I once heard described on Headfi as "bass fart cannons".... so my predisposition of what a good headphone sounded like was a bit tilted to the basshead side.... With all the hype I expected something similar but different (you dig?) But plugging in the HE400's I was taken back initially.... They were clear, very clear and very crisp.... the bass was there but certainly not up with the D5ks or Pro900s... Its not a basshead can. But as I listened and listened I had that "AHA!" moment.... These things sound good... very good!
 
The HE400 sound is not lush or warm or thick like many dynamic offerings.... It is smooth but hangs its hat more on clarity and providing a balanced presentation of the music. Some have called it a bass heavy can but I don't see or hear that at all. Comparing it to the Pro900 and the Denon D5K its sound is much lighter and fast.... If the sound of the Pro900 is overly thick and bassy.... audio maple syrup.... then the HE400 is distilled water... faster, refreshing, clearer but it doesn't lack for musicality.... What one does discover listening to this planar magnetic headphone is that despite having a super clean and clear treble, the slightly more forward and engaging mid range gives it a very "LIVE" presentation. It does not have that heavy full bodied pulsating rhythmic drive of similarly priced dynamic cohorts, but that livewire midrange provides this growling power to guitar driven rock that makes you want to listen to music. That is good enough for me!
 
Shortly after this I purchased the planar magnetic darling of Headfi, the Audeze LCD2. I was originally assuming that the HIFIMan can would lose its luster after the LCD2 arrived but this was not so.... Mind you the LCD2 has a lovely way about it... a beautifully resolving sound and penchant for low volume listening... the ease/ effortlessness with which the LCD2 can play the most complex and formidable low frequency passages is amazing.... I give credit to its lightning fast planar membrane.... It sounds wonderful with jazz, oldies, and classic rock.... but what I discovered after weeks and weeks of comparing the runt of the Hifiman planar line with the Audeze cohort more than twice its price is that with more up tempo guitar driven music the HE400 actually provides just a bit more impact to bass (especially with less than reference sources) and there is this "LIVE" factor to the mid range that gives it a more realistic sound with guitars.
 
Now I am splitting hairs here to draw differences but I saw the LCD2 as sounding more like listening to music at home while the HE400 was more like being at a show. Saying that is a very stern criticism of the LCD2... I am trying to paint a very thin line (a very small deficiency) with broad strokes but I heard it so what am I to do. That ever so slightly tipped up mid range response on the HE400 makes it just a bit more involving and immersive. The LCD2 holds you back ever so slightly from the music and thus can cause disengagement with mid range focused guitar rock.... Considering the better part of my library is punk, rock, and alternative... the HE400 is actually the better all rounder of the two.... What is more is that while the LCD2 can give you ridiculously well resolved low frequencies, I mean it mines the depths of a song to absolutely subterranean levels with perfect texture and resolution, the HE400 actually provides a bit more punch and impact to its low end despite being a bit less confident in its resolve. The HE400 is prone to get a little tizzy on some heavy low end stuff where the LCD2 holds crystal clear.... but the HE400 makes up for its slightly messy presentation with more punch and dynamic weight.... you can hear it with the Audeze but you can feel it with the Hifiman. This desire to meet you halfway is what makes the HE400 so special.... It is not as euphonic and lush as the HD650... but it does sound similar in a lot of ways, in that its presentation is on the polite side of things compared to very forward and bass heavy cans like the Denons and Ultrasones. However in terms of accuracy vs. impact it has found an amazingly intoxicating balance that stays fun while never getting fatiguing. The LCD2 offers you resolution and clarity in spades.... Its technical speed is unmatched by the HE400 (which is how it ought to be) but the LCD does take maybe a few step further away from the stage and this slight recess strips away enough of the emotive experience that the HE400 has a justified place in my collection.
 
It is certainly not the last word in headphones but considering its price and the competition in the $400 +/- market it is an amazing performer. In the right setting with enough current feeding its drivers, it is an outstanding all rounder.
 
HAND WRINGING
 
I have one maybe two gripes with this headphone and they have ZERO to do with its sound quality. One is the weird reverse polarity coaxial connectors used to connect the cables to the cans.... The connectors are actually a pro television and radio fitting for antenna connections so it is an odd choice.... and very difficult to source. More importantly is that twisting the cable over and over to connect and release the cables is bound to eventually cause a short or some other form of damage in the cable.... My particular model came with a 6 foot Canare quad OFC cable and after connecting and disconnecting a few dozen times the collar on the cable side of the connector actually pushed through the back of the stem and fell off.... rendering the cable dead.... Hifiman was quick to send out a new replacement cable to me (Hat tip to Vince at Head Direct!) but if there was one thing I would change it would be that. Another line of defense that I may likely pursue is Toxic Cables adapters. If you buy a cable from him with say mini XLR terminations for Audeze cans he can build a set of adapters for Hifiman connectors so you can bypass the twist connector all together. You'd have a couple of odd little earrings dangling off the bottom of them when not connected to the cable but... This should only bother the most retentive of people in the hobby. The other mild nuisance is that the logo and markings are all painted on the headphones..... Thus after a few short months of handling them, the L & R designating which side is which have all but rubbed off.... The headphones appear to be perfectly symmetrical in build so I don't know that it changes anything to wear them either way but I opted to tag the stems with red and black sharpie to keep track. However it'd be nice if they could find a more permanent solution for marking the sides.... and the brand.... I've got to believe that eventually the "Hifiman HE-400" marking on the blocks will go to the wayside as well. Beyond these minor grievances I am superbly happy with this headphone.... It is a worthy adversary in the $400 realm and beats the snot out of its similarly price AKG, Beats and Grado adversaries... The HE400 is an opportunity to get some of the planar magnetic sound for significantly cheaper spend than normal. It is worth every penny. You will not regret it.

I really expected to like this as it seemed to be an audiophile favorite here. I listened to it for a few days to ensure that burn-in could occur, whether it be my brain of the headphones themselves.

The problem with this headphone is that it's super harsh, harsher than the DT990. And interestingly it sounds dark.

I don't know how they pulled that one off. At least the bass is fantastic, typical of orthos, but at this point, that bass extension and slam is pretty much useless due to that massive treble spike I'm hearing around the 10K+ region.

This is my first puchase of "audiophile level" headphones. I was looking for cans which can play "every genre" included traditional musics (gamelan from Bali & Java).
Purchasing done mainly based on internet review. It's a rather risky desicion for $400 for me
 
But, it's really whorted the price. I've burn the cans about 40 hours now, and they're getting smoother and more transparent. Especially for the highs. I use Marantz PM5004 amp and mostly FLAC file. They sound soo beautiful.
 
Jazz, rock, classic, acoustic, gamelan, bamboo music just so alive. I only miss a little from female voices. And suprisingly, even my rockboxed sansa clip plus can drive this cans beautifully . Great.
 
Overall, this's excellent price/performance cans. And sound very fun. I need a shorter cable too

I've been wanting a bassy open headphone for a while and after a bunch of research I decided on the HE-400. I normally have no interest in high end headphones because they lack bass, but from what I've read the HE-400 will give me a decent amount.
This is a quick impression from a basshead's point of view since there's already plenty of reviews, but most reviews are from audiophile who don't normally use and listen to bassy headphones.
I used the new FiiO E12 (the no bass version) for this impression with flat EQ on my iPod video 5.5G.
I use this set up because I have multiple listening spot in my house.
 
Value:
Definitely worth the $400, I got mine from Justin @ headamp.com for $335 shipped, factor in the sound and build and it easily worth more than $400.... If you're an audiophile. For bassheads it would depend on how much bass you're looking for.
 
Audio Quality:
I love the sound of the HE-400 but I do wish there was a bit more rumble, but I wasn't expecting it since it's an open audiophile headphone. The sound quality wasn't the leap in sound I thought it was. It's better than what I previously had but it wasn't that much better it's more of a different better. To my ears the HE-400 kinda sound like the portapro (which I love btw) but better everything. The mids are great and highs are nicely details without piercing my ears like most audiophile headphones. Vocals are nice and clear. 
Now for the bass. It's good bass, clean, fast and just loud enough but no way is it basshead level.
For audiophiles who don't normally listen to bassy music or use basshead headphone will call the HE-400 bass heavy. For us basshead it's not even entry level. It's nice bass but lacking in quantity even with a bass boosting amp. The FiiO E12 with it's weak bass boost did not do much in uping the bass quantity. The quality of bass is great though.
 
Design:
I love the design of the HE-400, it easily one of the best looking headphone I've used. Build quality is solid too. The cord is the only issue I have, it's too long and too stiff.
 
Comfort:
I personally did not have any issue with comfort. I had mine on for 3 plus hours without any discomfort, but I don't normally have issues with uncomfortable headphones (except the V-Moda crossfade and Shure SRH750DJ) so take what you want from that. 
 
Overall:
I am a basshead but my demand for bass is not what it use to be. I don't want bass all the time, but when I'm in the mood for bass I want a lot of it. The HE-400 is good enough for normal listening session, but when I'm in the mood for some serious bass I usually skip the HE-400. When I first started here I got a lot of recommendation from audiophiles saying this and that has a lot of bass, but when I buy them they lack bass big time, I realized most audiophiles have a very different view on bass. What's lacking to bassheads are a lot to audiophiles. The HE-400 falls into this category.
Overall I'm happy with the HE-400. It sounds great and even though it's not basshead level, the bass is good enough.
I'm currently looking into other amp that will max out the HE-400 so I might update this later, but for now the E12 is not doing the job I bought it for so back it goes and will be replaced by the C5.
 
 
EDIT:
[02/20/2013] Today I decided to use my E07K, I max out the bass(10) and gain(12) and the HE-400 gave me a good rumble, but once I up the volume to about 40 (65%-70%) it started to distort. 
At least now I know the HE-400 can give me a bit more bass quantity with the right amp. The E07K is not the right amp, SQ suffers when using this amp.
I have come to a conclusion, this headphone will never truly satisfy a true basshead

I still recall the day I placed my order for the He-400's, I waited with anticipation and days seemed to last an eternity. But the moment they arrived and I connected the dac to my computer, I was severely disappointed. Needless to say I listened to them for about 30 minutes before I put them back in the box and left them there. My father is also pretty passionate about audio and knew beforehand that I had ordered these headphones. When he asked about them I just told him I'm returning them, he was curious as to why so I hooked them up for him. He listened to them and looked at me and said why don't you like these?
 
They sound extremely clear and detailed. I explained to him that I was expecting them to sound incredible. That same day I processed my return but the company I bought them for offers a 60 day money back guarantee. So I decided I would give them another try and eventually the sound grew on me, and I began to appreciate the clarity and the separation of the instruments. The amount of detail I noticed subtle things in my music that I had never heard before and I had never experience sound stage this good.
 
However for the many great things that the He-400's do right they also have their flaws. My biggest gripes with these headphones for me personally were the build quality and the comfort. These headphones were probably the most uncomfortable pair of headphones I have ever owned. They are heavy and produce a lot of clamping pressure. In all honesty I could not use these headphones for more than 30 minutes before I started to feel strong discomfort. The other fault lies in build quality, in my opinion these headphones don’t look or feel like $400 dollar headphones.

***Update 1/9/2014
 
I've written a longer review elsewhere in the forum.
 
In short, these phones' offer tremendous sound for the money. Well-textured, virtually transparent, fast attack, with a balance tending toward "bright". They will present your most complex recordings with an effortlessness you've likely not heard before. The bass is incredible - in the sense that it can be punchy, and very well extended. You will notice bass lines differently with these, and sub-bass frequencies skipped by most headphones will be replicated here with little distortion. If you happen to listen to everything (like me), you know how important it is to have a balanced sound, and these have it. These phones are also known to respond very well to EQing. I do EQ treble downward about 2-3 dB as it can be a bit overemphasized with some genres. I also like to add about 2-3 dB in the 50hz area to add some weight to the bottom end. It is great to feel like I have such control over the 'final sound'. But sadly, some of this is a result of the unforgiving nature of the HE-400s - they will not 'fix' poorly mastered recordings or force their sound onto them. In a sense, they are only as good as your recordings are.
 
But these have convinced me that planar technology is the real deal, I doubt this sound can really be emulated by traditional driver technologies anywhere near this price. Overall sound will scale with a good amp / DAC (~half watt or so), though they will get adequately loud with most common 1V sources like laptops and phones. These cans can be a bit "fatiguing", but much of the fatigue has been corrected with minor EQ tweaks and modding the stock pleather pads / using the velours. Coming from German phones, I actually would rather have a more aggressive sound and experience some fatigue than suffer a 'laid back' sound when I am in the mood to head bang.
 
Would have given them 5 stars except for a few things. For one, I think the stock cord is a bit thick and stiff, and also way longer than necessary. After about a year of ownership, there is some fraying in the stock cables where they connect to the cups. I worry about long-term survival of the threaded connectors on each cup, but they are holding strong. In this price range, a nice metal headband and cup holders are welcome, but some slight "creaks" from the plastic are not. Other users have disconnected cups from the headband, as apparently, they are only glued on. Earpads easy to remove, and the tabs are not breaking, which has been a blessing as I have swapped the pads on and off many times at this point.
 
Comfort could be better - the clamping force is a bit intense at first, I needed to bend the headband slightly. I quickly swapped the thinner leather pads for the slightly thicker velour from their more expensive models. Leather or velour, the pads are quite stiff though not uncomfortable. I have since 'modded' the pleather pads by removing the foam spacer rings and cutting holes into the backside of them to improve damping. It improves on the feel of the pleather and the sound and is worth doing, but I still like the 'breathability' of the velours more, and they are still an upgrade in that sense (plus they sound better than stock pleather). The cups adjust and swivel, but are stiff and should be adjusted with care (pinch the headband and logo as you do it). Headband padding is too thin and I experience pain once in a while. It also gives me 'headband hair'. These phones are only 6 oz heavier than my lighter sennheisers (HD595), but they "look" and feel a lot bulkier. The threaded cord/cup connection grazes my shoulders when I turn my head which I can't imagine is great for the phones or myself.
 
But I can listen to these for hours anyway, the great sound just makes up for a lot of shortcomings. They are excellent headphones overall, but objectively, the comfort is simply no comparison to Sennheiser, which is often forget-they're-on-my-head good. The slightly aggressive sound may not be for everyone, and many are 'underwhelmed' by the sound at first (they seemed quite lean to my ears initially). But the HE-400 satisfies me much more than any phones I've owned before. That said, I knock a star off design for weaknesses in cable attachment / bulkiness and materials (stiff foam, possible cheap plastic), and 1.5 stars off for a sound which is fatiguing, a headband that can seem harsh, and cups which are hard to seat comfortably on my head (compared to other phones from which I have not experienced these issues). But if sound quality were the main criteria, good luck finding a better pair of phones for $400. The HE-400s are the real deal.

The title is not exaggerated either, but of course to get the HE-400s to that level you need at least a decent DAC and a tube or hybrid amp like the Schiit Lyr to even hear what they truly can do. Otherwise most amps will will work just fine with them! I have tried them with my Schiit Asgard solid state amp for weeks, but felt they need more that 1watt per channel (the Lyr has 6!). The gain in sound quality is extreme enough for most people probably, but as you get to really appreciate these cans, you will want to get everything out of them.

Simply put (without resorting to headphone comparisons which I did against the HE-400 which can be seen here: http://www.youtube.com/watch?v=9zdHTN5ysZQ ) the 400's have Superior soundstage, detail, and balance while still being exciting. There is only one other Planar headphone on the market now (Fostex t50rp and it's mods like the mad dog) but it doesn't touch the 400, HiFiman made the pinnacle of price/performance.

You may think $400 (or less used!) is a lot for a pair of headphones, but when you consider it's top of the line tech that headphones many times it's price use, you know you've got a smoking deal.
 
Note: My 400's have the MUCH better than stock velour pads and a Q-Audio braided cable.