I've been trying to write a review of these headphones since September 13th, but I've been completely stuck.  Simply put, I'm almost embarrassed by how much I love these headphones, and I find myself unable to write what I consider a critical assessment.  My favorite reviews and reviewers on Head-fi are those that are able to strike a balance of criticism and praise.  If anything is too one-sided, I lose trust in what I'm reading. So- I'm stuck...
                I've had this happen before, with my main speakers, the Ohm Micro Walsh Talls.  To me, they are the epitome of a mid-range speaker that can be truly end-game.  I bought them as a compromise between quality and convenience, and after five years I'm still very much aware that I have no need or desire for another set of speakers.  I think that the Hifiman HE-400i's are an even better value, and a better performing transducer, than my beloved Ohm's.  So I guess I should toss objectivity to the wind, and tell you why.
 
                Bass
 
                I might as well start with the Achilles Heel of headphones: bass.  I feel sorry for headphone manufacturers when it comes to this aspect of their work.  The biggest problem with bass is the variety of styles and types  that they are required to reproduce.  There is the bowed, upright bass in classical music and the plucked upright in jazz and other genres such as bluegrass.  Electric bass falls into various categories such as the Jazz Bass sound in jazz, funk, slap, and modern recordings, as opposed to the P-bass sound found in rock and blues.  Yet another type of electric bass is the Rickenbacker sound of early Geddy Lee, Yes, and a diverse blend of metal and progressive music (and of course, each of the three can be found in other genres, but I'm sticking to generalizations and cliches).  Then there's the effect-laden bass of dubstep and electronic music, synthesized bass, keyboard bass, sub-bass, movie soundtrack bass, explosions, and even ambience in live recordings.  Bass is very, very difficult to deliver across all of these and other possibilities.
                 When it comes to audio, even though I'm a bass player, I'm no bass head.  I need accuracy and detail in my headphone bass presentation.  One of the most disappointing headphones I've owned is the Hifiman HE-5LE.  Don't get me wrong, it was a fantastic headphone.  But after a few months, I realized that the awesome lower-octave of those cans was to the detriment of the midrange and overall balance.  I found myself greatly preferring the Grado SR-225i's bass presentation, which almost completely rolls-off the bottom octave and a half. The 5LE's were great for movies and soundtracks, and were like wearing subwoofers on my head, but it overwhelmed the other stuff that I listened for, including vocals and percussion.  Their replacement came with the Alpha Dogs, which extended deep, but honestly lacked the heft and weight that is present in a lot of recordings.  If the mastering is perfect, the Dogs are hard to beat, but they miss something in less-than-stellar recordings (I do have them being upgraded to the Primes at the time of this writing, so I'll hear if they do a better job in a couple of weeks).  The 225i's present the detail and nuance of the various types of bass, but fail to deliver sonic bombast when the recording calls for it.
                The 400i's, for me, are the perfect compromise.  Yes, they lack truly  serious "oomph" below 40 Hz, but they do have moderate "oomph".  They don't quite have the fine detail of the 225i's or the HE-560s that I auditioned.  But they are very, very close.  I can easily hear the difference between a Fender Jazz, Fender Precision, or the various Rickenbacker tones for electric bass. Synth bass has authority, and orchestral bass is almost perfect.  The 400i's can swing from the tasteful bass in the Cowboy Junkies' Crescent Moon to Kyuss' Welcome to Sky Valley, and then all the way over the Return to Forever's Romantic Warrior.  They are virtually effortless and transparent in this regard, and while they don't plumb the absolute depths like other headphones, they have yet to fail on anything I've thrown at them.
 
                Midrange
 
                When I think of mids, Grado comes to mind.  I just love them.  Models I have owned or heard over the past year include the 225i's, iGrado, RS1i, and GS1000e's.  They are just so easy and casual with mids, and with the exception of the GS series, possibly the ultimate rock headphones.  I'm sure many readers will disagree, but most of us can admit that a lot of rock fans love Grado, and vice versa.
The very first song I played on the 400i's as Into the Void by Black Sabbath.  It's just my ultimate fuzzed-out guitar song, and the Grado's present that song perfectly.  My first thought with the 400i's was "Holy *###, they sound just like the Grado's."  The next couple weeks was pretty much a steady diet of hard and heavy guitar rawk, and I was never disappointed.  Full, rich, saturated tone came out of these headphones, and I knew I was smitten.  The 560's did not present this kind of music so naturally and effortlessly, and the 5LE's couldn't even begin to do so.  The Alpha Dogs are too darn polite and restrained for me to really get my pulse moving.
                If there is one minor nitpick with the 400i presentation, it's with vocals, both male and female.  This is the area that reveals that they are not neutral, and that's with a slight bump I hear in the lower mids that adds a measure of thickness to voices.  It's not unpleasant, but the Alpha Dogs are my choice when it comes to vocal/choral recordings.  Other than that, or even because of that, the mids on the 400i's are so subjectively pleasing that I can live with just about any other shortcoming.
                Treble
                These are not the most extended, transparent, or "airy" headphones out there, not by a long shot.  However, like the HE-560's, they seem to walk the fine-line between too much and a slight veil.  Somehow, the zing of a cymbal crash, the slight squeal in some female vocals, and the piercing wail of a guitar solo are all presented fully without harshness or added sibilance.  Like the bass, this is a Holy Grail of headphone listening for me.  I simply don't need to change volume like I do with other cans if things get too bright, and I don't need to turn them up to hunt for detail.  The word that comes to mind is 'balance'.
                Image/soundstage/depth
                I don't really expect much of the above factors from headphones.  It could be one of the reasons I am rarely disappointed, and I consider myself lucky for that.  Still, I am aware of them, and as far as I can tell for the most part the 400i's are perfectly average for these, with one exception.  The depth presented with the 400i's is amazing to me, and I don't know how to account for it.  The Alpha Dogs are also good for this, but the 400i's kick it up a notch.  One of my favorite recordings for depth is Kill the King from the first album from the Masters of Reality.  It is a very layered and detailed recording, and the image out of the them was so good, I thought I had my main rig on.  I had to take off the headphones to verify that I was just listening to headphones.  The Alpha Dogs might have more detail, but for some reason the 400i's come across to me as holographic if the recording calls for it. That's why I can tolerate the mids in vocals, because singers usually come across as right in front of me in a way I have not experienced since I hard Magnepan 20's about 15 years ago, or Apogee Scintilla's. But honestly, ever since I heard and owned Ohm F speakers, soundstage has never been a serious concern for me, because I don't think anything can throw an image like an amazing omni-speaker like that. I don't even try...
                The Real Reason
                Everything I've written is well and good, but none of that combined is the real reason I gush over these headphones.  I gush because these observations and experiences are based on listening to them with the HP out of my Toshiba Satellite laptop using JRiver MC 20, Spotify, and recently, Tidal. If for whatever reason I need more volume than the Toshiba can supply, I use the FiiO E10.  In both cases, the experiences meets or exceeds my subjective experience with a Burson amp with either a Shiit Bifrost Uber or the DAC straight out of my Oppo BDP-103, and combined with the Alpha Dogs, HE-560, HE-5LE, GS1000e, SR-225i, or the RS1i.  Additionally, the 400i also bests the Sennheiser PX-100II and the iGrado with the same laptop. The mere idea that a $500 planar can do that with such a humble rig blows my mind.
                I can't explain it.  My degree isn't in engineering, it's in addiction psychology. I admit, it could be due to various biases, including expectation.  In the end, I don't really care, since I don't listen to headphones for any professional reason.  All I know is that the Burson is complete overkill for the 400i's, as is the Schiit Magni.  I also cannot discern one objective difference in anything between either of them and the laptop/FiiO combination: vocals, percussion, basses, soundstage, imaging, or anything. Believe me, I'm not trying to state that anyone else will have the same experience as I do with such a low-power, seemingly low-resolution rig.  The fact that I do is insane enough...
 
Postscript
                One last thing, in the interest of full disclosure.  When it comes to amps, dacs, cables, and modifications, I'm pretty much on the objectivist side of things.  I don't ascribe to hardware modifications in headphones aside from the tape mod with my 225i's.  To compensate for loudness contours and personal preference, I rely an EQ, both graphic and parametric (but not at the same time, of course.)  My adjustments are 3 db or less (mostly), and involve cutting rather than boosting frequencies depending on the volume I'm listening at or the 'signature' of the headphone. It's just how I like to do things.
Update 3/31/16
Wow, as it really been almost a year and a half?  My, how things change.  I've added new gear like the Cavalli Liquid Carbon, ventured into balanced-cable land, and tried a few more headphones.  I thought the Meze Classic 99's might un-seat the 400i's as my favorite all-around headphone, but that fear was short-lived.
I am still every bit as enthusiastic about these cans as I was back then.  In fact, even more so. The Primes continue to best them in absolute clarity, detail, and transparency.  But for me, the 400i's hit that razor-thin line between mid-fi and Summit-fi.
No headphone or IEM has come all that close to supplanting the 400i's on my personal "Wall of Awesome".  One thing changed though: I have heard a difference in balanced configuration, with a high quality amp such as the LC, which causes me to revise my earlier statement about scalability.  They do scale, and mightily so.  I also am not so enamored with them out of an iPhone or other low-power source.  They sound good, but not great, especially compared to the Meze.
Next up, I ordered the new Sennheiser HD-800S's.  It will not be a fair fight, I know that. I do not expect them to hold up to TOTL dynamics like the Senns.  But it will be an interesting experience...
In the meantime, I still stand by my 5-stars.
(Oh, and I turned in my 'objectivist card' as soon as I heard the Liquid Carbon.  Just an FYI...)
 

Setup:

1. DAC: Aune T1 with upgraded 6922 tube. Purchased with the HE-400, great little DAC/AMP. Frequently compared against the ubiquitous Schiit Modi/Magni stack.
   
2. AMP: Emotiva X-Mini A100. Normally a speaker amp, but this one was modded to support a headphone jack. With two 150ohm resistors in series - supposedly a very decent amp for orthos such as the HE-500.
   
3. Software: Foobar 2000, and FLAC quality rips.
   
4. Burn-in hours: About 100hrs, wasnt able to get in a full 150hrs due to selling the HE-400s. 
   

*Both the 400 and 400i have Focus Pads and have been grill modded.

 

 

 
 
 

Bass: After reading multiple reviews, and forum goers opinions - the bass on the 400i's holds up remarkably well against the HE-400s. Much better than I thought it would.

The 400i's dont carry quite the body, but it is very much detailed, more punchier and taut. I had a few songs in mind that I would compare against:

1. The first one being the Tron:Legacy OST, specifically "Recognizer" the first 25 seconds there is a run of all kinds of sub and mid bass and the 400i presented bass that was controlled, layered never bled into the mids.
   
2. The second track was "The Game Has Changed" - and the 400is handles a barrage of bass slam at 20 seconds in without breaking a sweat. Discerning the onslaught of quick bass in the front while being able to render the violins and orchestra in the background seemed easy for the 400i. The 400s hit you in the chest a bit harder, but the 400i's was more refined.
   
3. Next song was Steve Aoki's "Rage the Night Away", strictly hip/hop EDM (i guess) - and at the 15 second mark there is a "drop" and again the 400i hits it pretty hard. Detailed while taking advantage of ortho speed, it is very very fun - found myself easily dancing along just as i did with the 400. The 400 did have slightly more body though, and hit with pinch more authority. A bit subtle, maybe tough to tell the difference if i wasn't directly A/Bing the two.
   

The 400i's Achilles heel is its bass, or so I thought. Maybe my expectations were really low coming in, but the 400i's can hold its ground.

A 9 to the 400's 10 when it comes to impact, but where it loses in output it makes up in detail and maturity. It doesn't need to be loud because it knows it just knows its more refined. Bottom line I was pleasantly surprised that the bass wasn't as bad as I feared and was in fact a very very small price to pay.

 

Mids: This is where the 400i's just straight up outperform the 400s. Orchestral music are a step up on the 400i's.

1. Frozen OST - "Elsa & Anna" - Hey, its a fun movie! Layered violins & brass, flutes & clarinets are presented in a level of clarity that the 400's aren't quite up to par. You get a sense that youre right in the pit of the orchestra - its very easy to get swept up in the music. The 400s are great as well, just a bit veiled compared to the 400i's - it also has no problems with instrument separation in my ears, but the 400i's just seem more pristine.
   
2. Mozart: Piano Concerto No. 20: Allegro Assai. A masterful piece that incorporates a very fast piano intro, then segue-ways into a flurry of string work accompanied with woodwind and brass. Then at the 0:56 mark it again features a drop to a single piano which shows the dynamic range and speed/decay of the 400i. The 400s also portray this very well, but with same veil and slightly less natural sounding. I can picture each piano hammer strike its string a bit more clearly compared to the 400.
   

The 400's mids are noticeably more recessed, especially when doing a direct A/B comparison. Slightly veiled where the 400i's mids are presented without any obstacles.

 

Highs & Sibilance: The 400's biggest weakness, an abrupt spike around the 10k region which wreck havoc on female vocals. The dredded "ess" sound reared its ugly head quite frequently on the 400s. Apparently the 400i corrects this problem.

1. Ellie Goulding "Burn" - this brought out the sibilance in the 400s almost immediately. This was my goto song for sibilance and damned near impossible to listen to without EQing the 400s by about -4db.

I was hoping the sibilance would magically disappear with the 400is, they didnt. It's better ut the "ess"es sprinkled this track all over the place. Turns out the 400i's do have a slight bump at around 9k, but its much more manageable and rounded compared to the 400s.

I only notice sibilance once in awhile, and when I do I conclude its the track haha.

1. Taylor Swift "Stay Stay Stay" - A really fun song, no signs of sibilance here. The 400i's are a touch more sparkly than the 400s, similar to how the mids are veiled, the highs are shown with a bit more shine.

The 400i handles the highs much better than the 400s, but this just shows how bad the 400s are as opposed to the 400i's doing it perfectly right.

The 400i's arent as fatiguing as the 400s which can sound downright shrill on some tracks. I may still need to EQ by a couple dbs, we'll see.

 

Sound Stage: Another weakness of the 400i's is its more intimate sound stage against other open backed headphones, not just the 400.

The 400i does have a slightly smaller sound stage, using YouTube's "Virtual Barber" at around 2:10 the barber snaps his fingers on both sides.

Closing my eyes and placing my hands to where it feels like the source comes from its - "left" snap feels about just under a foot and a half away on the 400s and about 2-3inches closer on the 400is (i move my hand ever so slightly closer).

I would've liked a larger sound stage, the 400's do have an advantage here. Luckily the 400i's do have better depth, I can slightly make out layers of an orchestra more precisely.

 

Vocals:

1. Male - Maroon 5 "Misery (Acoustic)" & Bruno Mars - Not the most manly vocal range, but both Levine's and Mars Tenor/Falsetto timbre do come off slightly more natural on the 400i than the 400. Both do very well with male vocals imo since sibilance isnt really an issue.
2. Female - Adele "Set Fire To The Rain" (Live at the Royal Albert Hall). If I close my eyes, it's almost as if I'm right up on stage with Adele. Her vocal range isnt as high as Ellie Gouldings but her force and power does come through rather well. I dont think the 400i's really get in the way of conveying her emotion. Pretty happy with how she sounds on the 400i. On the 400, her vocals sound great as well, but can be harsh for female vocals that are on the Soprano/Vibrato range

I think the 400s portray live recordings pretty well with its slightly larger sound stage, but the 400i's present timbre more naturally. Where the 400 wins n EDM, it loses when it comes to vocal presentation.

 

Comfort: No contest here, 400i buries the 400. On hand they feel pretty similar in weight (360g vs 440g) but the suspension style headband really does spread out the weight well across the top of the head.

It doesn't quite "melt into your head" but it is significantly more comfortable. I wore the 400's for hours at a time, but the 400is are a league more comfortable. Coupled with a less fatiguing sound, the 400i's a very easy to wear. The gaudy cable that comes with the 400s is comically long and heavy, it cant help the 400 when it comes to comfort.

 

Overall: Purchased for $395USD from Razordog, the improvements in comfort alone is almost worth the gap in price over used HE-400s (~$225-250). The cleaner mids, smoother highs and punchier bass take the 400i at least a step above the 400.

I'm pretty happy with the 400i's in all areas, its only weakness to my ears is its sound stage unfortunately, its not bad by any stretch but I wonder how a more spacious headphone like the HD800 sound like. Luckily the 400i also look sexy as hell, and order of magnitude better than the 400s. It even makes the HE-560 look old fashioned and boring in comparison.

I hesitate to call them a "mid-fi" headphone, I'm sure they're a shade under headphones like the HE-560, and Oppo PM-2 while being just outside the HD800s. I almost feel it beats the PM-1 and Alpha Dog in sound quality.

Overall the 400i bring fantastic clarity, detail and fun while being pretty damned comfortable.

 

The HE-400i is a very neutral sounding headphone, not much emphasis or recession anyway and high frequency extension is better than 99% of headphones. On the other end of the spectrum however, bass extension is linear until 40 or so hertz, then it begins rolling off. I think this is due to the way the earpads are dampened. Typically planars have very linear bass extension, but I don't think its that problematic, especially considering most open-dynamic headphones are much worse in this regard. One thing you would expect from a planar is a smaller soundstage, and the HE-400i doesn't fail to meet expectations there. While the soundstage doesn't feel clausterphobic, it lacks a sense of air. Songs that have big soundstage are conveyed decently, but ordinary songs are pretty stereo sounding in a very left and right way. I'm a big fan of huge soundstage, so the HE-400i doesn't exactly excite me with how it portrays the soundspace, but the imaging and clarity are very good, as well as depth. Timbre, texture, realism, etc. are some of the best aspects of the HE-400i, combined with the quick decay the sound of the HE-400i is just really fast and responsive, never gets congested in genres such as dubstep or metal.

I think they're quite good, but not for everyone. I bought them because I wanted a more open and comfortable counterpart to my JVC FX850 IEMs. Based on technically merit alone, they're not much superior to the JVCs (well, FR is much more neutral) and comfort-wise I have a very large head so the clamping force makes them uncomfortable for me. Many others who I've had wear them say they're remarkably comfortable, though. I think I'm going to sell them and try the HD600, AD2000, DT150 or K612. 

I posted this over in another section, so i realize it should be here as well....     
 
 
 
 
 
 
       I have not really written a headphone review before, but after participating in the HiFiMan HE400i touring event (basically, they lent the headphones to me for a while) I have decided to give it a go. Please forgive me if my thoughts are scattered, but I’ll do my best.
 
       I should probably start with a little info about myself. I am a long time music lover, who used to sell audio equipment. (Anyone remember Nobody Beats The Wiz?) While I make no claims of expertise, I will say that I am not entirely unfamiliar with evaluating sound.  (How accurate my interpretation is will be up for debate, I’m sure.)
 
       Starting with the build quality, I think HiFiMan has a given a solid offering. Any plastic included is sturdy and attractive, as you might expect at this price point, ($499 USD as of this writing). The ear cups are somewhat fingerprint prone, but it’s not very obvious given the dark color, and they clean easily enough with a cloth or tissue. My set was solid, devoid of squeaks or clicks, with flawless fit & finish. The cable is thick with a nice braided cloth sheath over the wiring, which is not easy to tangle. The fabric & leatherette cushions are plush and well stitched, and the metal tension bar is quite solid. The only part that didn’t inspire my confidence was the position sliders that adjust the size of the headband. Although they adjusted with a solid click, the piece seemed more flimsy than the rest of the headphone. I will note that I didn’t experience any difficulty with the adjustment through my weeks auditioning them.
 
       …And what wonderful weeks they were! The comfort level the HE-400i affords is better than I would expect from a headphone weighing about 13oz. I was able to wear them for hours at a time, without experiencing any notable discomfort. One of the changes HiFiMan made to the HE400i (updated from the HE400) was the headband, and I can say with confidence that the clamping force was never harsh on my (small-ish) noggin. The new design distributes the weight across a strap below the top bar, which holds the tension. While I doubt this will win any style awards, it does the job admirably (and open back headphones such as these are best worn indoors, anyway). My ears did feel uncomfortably warm on occasion, but that’s to be expected of any over ear (Circumaural) headphones.
 
       HiFiMan recommends 150 hours (!) of burn in time (letting music/white noise play through the headphones continuously) so I deferred all serious evaluation until then.  I’ve never been a big believer in burn in, but if the manufacturer requests it, I won’t argue. Another (potential) improvement HiFiMan made to the HE400i is an adjustment to the impedance/sensitivity, so that they can be driven by smartphones and the like. As a result I had no problems driving these headphones from any device. My Sansa clip, HP all in one PC, Fiio X3, LG phone and my Yamaha receiver were all more than capable of achieving an adequate volume without noticeably sacrificing sound quality, although on some tracks, the LG & the Sansa’s volume was maxed out. I found that the better the amp I used, the better the sound, of course.
 
       Sound quality is what most people spend their cash for, and I found that the HE400i delivers. This pair of headphones simply drew me into the music. That experience of “Gee, I wonder what THIS song would sound like through these” was an all too common occurrence, causing me to jump excitedly back and forth through my catalogue of music trying to re-experience everything. Anything I played through the HE400i was a pleasure, provided that the recording/song was a pleasure, that is. These headphones are nothing if not revealing.
 
       Bass impact was a touch less than I prefer on some songs, although I found them no less enjoyable. Stevie Ray Vaughn’s older recordings like Texas Flood or his album version of Voodoo Chile, had less “oomph “ in the bass than I generally like, but that is just my preference. The pitch and definition was stellar. The drums in A.H. Rahman’s Jai Ho from the Slumdog Millionaire soundtrack had texture and depth. Songs recorded with more mid-bass presence I think were better represented. I felt nothing lacking in the bass line from Queen’s Another One Bites The Dust, nor did I perceive The Possibilities Are Endless by The Teodross Avery Quartet as bass shy in any way. The HE400i could definitely reach deep when the recording called for it. The electronic bass line in Fatali’s recording of Homeless was pleasurably authoritative and deep. Even if the bass wouldn’t be considered the star of the show, I still felt it played the part extremely well.
 
       The midrange, I’d say would be where the HE400i shines the brightest. Pat Wictor, my favorite undiscovered acoustic, bluesy, folky singer, never sounded so good. The well recorded a cappella song “Raise My Voice and Sing” was airy and crystal clear. Redemption Song had Bob Marley sounding as nuanced and intimate as I’ve ever heard him. Female vocals were just as gorgeous, from Stevie Nick’s trilling vocals to Jewel’s airy falsetto; I was constantly getting lost in the songs.
 
       Moving on to treble, I found the HE400i to be smooth and articulate. Sufficiently revealing, without harshness, I found the treble well balanced with the rest of the spectrum.  Cymbals sounded natural, and guitars soared without sounding edgy. What I found most appealing was the sense of “air” and space I experienced. More than any headphone I’ve owned, the HE400i gave me a sense of the environment the artist recorded in. One of my favorite classical downloads is of Bach: Sonatas and Partitas, Bwv 1001-1006 by Oleg Kagan, and you get a distinct sense of openness from the venue through these headphones. Switching gears to AC/DC, even listening to a song as familiar (to me) as “You Shook Me All Night Long” had me take note of the echo/reverb added to Brian Johnson’s voice.  Song after song, I noticed subtleties I hadn’t noticed before.
 
       Obviously, I’m somewhat smitten with the HE400i, which is what prompted me to try my hand at a review. While I wouldn’t call these basshead phones, and the sound signature isn’t what I think of as “fun”…it’s not a v-shaped sound,  I still I found these headphones to be engaging, revealing, and for me, a delight to listen to. Although they aren’t perfect (what headphones are?) there wasn’t anything I played that I wasn’t satisfied with. Obviously, I highly recommend them.

 
I was fortunate enough to be picked for the review tour for HiFiMan’s latest planar magnetic headphone, the HE-400i, billed as an improvement over the outgoing HE-400 model, and slotting in at $500, $100 more than the HE-400.
 
The HE-400i arrived in sizeable, leather appointed box, much improved from the simple paper box the HE-400 was packaged in. Right off the bat, my expectations were raised in the best way possible and when I opened up that box, I was greeted with a much classier setup than that of the HE-400. I knew then I was in for an interesting headphone in the HE-400i.
 

Design and Build Quality

Honestly, my first reaction to the HE-400i when taking it out of the box was…“cheap”. I’ve realized since that it’s not anywhere near that clear cut. Compared to the beefier, heavier HE-400, the HE-400i is significantly lighter, featuring more plastic in its build and a bit less metal. Contrasting the HE-400, the 400i has plastic ear cups and yokes, compared to the resin cups and metal yokes on the HE-400.
 
The cups themselves feature a nice, chromatic deep purple finish that’s classier and more immediately distinctive than the HE-400’s dark blue finish, which was rather polarizing among HE-400 owners. Personally, I didn’t mind the blue color but I do feel the HE-400i benefits from the chrome purple finish.
 
The headband has been changed from a more rigid leather wrapped affair to a suspension headband system employed in headphones like AKG’s K7XX series.
 
But, if I had to pick one failing of the HE-400i’s design, it’s one that was carried over from the HE-400, the screw-on, mini-coax connectors that secure the cable to the headphones. I’m not one to switch my cables often and this isn’t a problem that rears its head particularly often for most people but attaching the cables can be a bit of a hassle, as the opening where the cables screw into the headphones is just too small for one’s fingers to get into comfortably to secure the cables tightly. If you’re a set-it-and-forget-it guy like I am, this’ll only be a problem once, but if you like switching out your cables for different situations (say, a longer cable for living room listening and a shorter one for bedside listening), the connectors are bound to be a nuisance.
 
 
But, in many respects, the design is still distinctly HiFiMan in that I wouldn’t mistake them for headphones made by any other company. Though the materials have gotten lighter and arguably cheaper feeling, the design itself is sound and as long as you take care of it, it should last.

Comfort and Isolation

Isolation? No. It’s an open headphone. About as much sound comes out as goes in through those open grilles.
 
Comfort is provided by way of HiFiMan’s new Focus Pads, a hybrid design of pleather and velour. I originally bought a set for my HE-400 before I received the HE-400i and loved them right from the start. The HE-400i with the Focus Pads and the new suspension headband, combined with the lighter weight is a very comfortable headphone that should last long listening sessions without much in the way of fatigue. I, for one, wasn’t a big detractor of the HE-400’s comfort, even in its stock form but for some, the HE-400’s heavy build made it uncomfortable for many people so I believe the HE-400i will be a huge step up for those people.
 

Sound Quality

First, a note on amplification. The HE-400i is, unlike many planar headphones, surprisingly easy to drive from a number of portable sources. HiFiMan claims the HE-400i is efficient enough to be run straight from a portable device like an iPhone without needing an external amplifier and, while this is certainly true, the headphones do benefit quite a bit from adding a dedicated amp to the mix. Without one, they tend to sound sound a bit thin and – dare I say – dull.
 
Now here’s where things get interesting. Let me just say right off the bat that if you’re expecting a direct upgrade to the HE-400, you’re going to be disappointed. The HE-400i does not build upon the sound signature of the HE-400, fixing the “tizzy” high end and making improvements elsewhere, maybe adding a bit more texture to the already lovely bass and bringing the midrange a bit forward. Instead, HiFiMan went a different direction in tuning the HE-400i, making something of a bridge between the outgoing HE-400 and more expensive and also retiring HE-500.
 
The low end presentation is the biggest and most immediate difference when comparing the two headphones directly. The HE-400i is less impactful and immediate than the HE-400 but still retains much of the texture and richness that I’ve come to love so much. But, that lack of “oomph” in comparison is what makes the HE-400i so very different from its predecessor. My main reason for purchasing an HE-400 was because of that planar driver bass, a low end that’s about as good as you’re going to get without dropping a grand on Audeze’s LCD-2. Sure, it’s nowhere near the last word in terms of quantity, but its quality is unparalleled by anything I’ve heard and many who own the HE-400 and other high end headphones would agree.
 
 
The HE-400i doesn’t deliver that same wonderful low end. At least, not in the same way. The detail is there, the depth is there, the wonderful texture is there (to a degree) but the impact and presence just aren’t. But, I’m saying much of this as a basshead. I can’t get enough bass and there’s nothing I want more in a pair of headphones than a rich, meaty low end. And there’s no doubt that the HE-400i has this, just not as much so as the HE-400. The HE-400i is most definitely a very good performer in the bass department, it’s just not as “fun” as its older brother. At least in my opinion.
 
The midrange is another big difference between the two headphones in that the 400i presents it more forward and fuller. I would say the level of detail is similar, with the edge going to the 400i. The presentation is surprisingly similar as well, with a fairly small soundstage (for an open headphone) but good imaging and spatial presence. The high end sees some improvements as well, with less of that HE-400 “tizziness” in the treble. There’s less sizzle and more sparkle, more delicacy in the chimes but with similar airiness and speed.
 
The HE-400i isn’t a direct upgrade to the HE-400, but that doesn’t make it a lesser headphone. In many ways, it’s better than the outgoing HE-400, from the more present midrange, to the less strident treble. Though it has a slightly smaller soundstage, the sound is a bit more coherent and naturally presented. The result is a more neutral and slightly less colored headphone than its predecessor but one that doesn’t have the same distinctiveness but is arguably more suited to a wider range of music.
 

Conclusion

What we have here in the HE-400i is a much more neutral headphone than its predecessor. At the end of the day, I see the HE-400i as neither an upgrade nor a proper replacement for the outgoing HE-400. Though that may sound negative, that’s not how it’s meant to be perceived. The HE-400i is a great, versatile, neutral and well nuanced headphone, just not in the same way the HE-400 was.
 
It’s almost like the HE-400 to 400i has progressed in a similar manner to that one guy you knew in college who partied all the time yet somehow managed to get good grades in all of his classes. Sure, he’s a bit rough around the edges but that’s his thing and he carries himself well while being a fun guy to have around. That’s the HE-400. The HE-400i is that guy, after graduating from college and getting himself a big boy job working in an office and wearing collared shirts and ties to work every day. He’ll still meet you for a beer after work, but he’s settled down and his rough edges have been smoothed somewhat. Maybe he’s not as fun and rowdy as he was in his college days, but he’s just as likeable nonetheless, albeit for markedly different reasons.
 
 
So, no, the HE-400i isn’t an upgrade to the HE-400, it’s a sidegrade, offering a retooled and retuned sound signature that, while retaining some of the characteristics that made the HE-400 so special, doesn’t carry enough of them to warrant being called a true “upgrade” to the HE-400. Again, this sounds negative, but it’s not, unless an improvement on the HE-400 while retaining similar sonic characteristics is what you’re expecting in the HE-400i.
 
Nonetheless, the pair I have is currently on loan from HiFiMan and I now have a choice to make. I can either ship them back at my expense or I can keep them and pony up and pay retail. I think I’m leaning heavily toward paying up and keeping my pair. They’re not an upgrade to the HE-400, but they sure are a nice complement. For $500, the HE-400i is a great headphone that, while not without its flaws, is certainly good enough to stand on its own.

The 500 dollar HE-400i is the entry level headphone that is part of Hifiman's latest line of single-sided planar magnetic.  Its purpose was to replace the hugely successful HE-400, while providing a sound quality closer to that of the venerated HE-500.
 
Having had extensive experience with the HE-400 for over 2 years, and my current goto headphone is the HE-560.  Sadly I have no experience with the HE-500, but it seems that from popular impression, the HE-400i is very, very close to it in terms of sound quality and presentation. 
 
 
To begin with, the build of the HE-400i largely mirrors that of the 560, and is representational of Hifiman's new efforts to make their headphones lighter and offer vastly superior comfort over their previous headphones, shattering any preconceived notion of planar magnetics being hefty and unwieldy beasts.  Although the plastic cups remain unchanged over the previous HE series form-factors, and although the same screw-in cables remain unchanged to many users' tears, the new headband with its suspension strap, and the lighter weight of single-sided drive makes this headphone miles better in comfort compared to the HE-400, and I can only assume an even larger disparity with the hefty HE-500.  The square, metal band that makes up the headband juts out from your head when these headphones on your head, and it makes the HE-400i a somewhat comical looking headphone, but the exposed metal band also means that stretching the corners out to adjust clamp to your liking is as easy as it gets.  In short you'll find these to be an extremely comfortable experience.  One note about the earpads is that their inner cavity is overall smaller compared to the previous Hifiman pads: the focus-a offers a slightly smaller opening than the focus pads, but have a lip for your ears to tuck in to, overall both pads have about the same volume inside for your ears.
 
 
The sound of the HE-400i some of the good aspects of the original 400, while improving in general balance by a considerable amount, although sadly sacrificing a couple of the original 400's best strengths in the process.  Like the original 400, the 400i shares a very warm signature, with a mid-treble peak centered around 10khz that will add sparkle and depth to its sound to avoid it from being too claustrophobic sounding.  While the original 400 had a hugely depressed region centered around 5khz-- an area that is responsible for the bite of a lot of instruments, especially brass and strings, the 400i has a secondary, mild elevation of this area compared to its upper midrange (2-3khz), which prevents it from being as dark and lacking as the 400 when it comes to sounding energetic.  Just like the 400, the 400i has a mid-treble peak, only this time around it's not as elevated or as harsh as the original.  Make no mistake that it is still above neutral in the mid treble though.
 
Some of the best aspects of the 400 still remain with the 400i, including a very yummy and textured lower midrange, and a very balanced but strong bass that extends super deeply without excess bloat or distortion. The 400i's upfront lower midrange will make for fun listening if you value the rich fundamental tones of acoustic instruments.  The hyper-detailed HE-400 sound is still present with the 400i as well.  Instrument separation is off the charts as per usual with any planar magnetic design, and the articulate and emphasized mid-treble help bring out texture and small details out of your recordings.  Furthermore, the weird midrange distortion that made the 400 somewhat messy sounding at times is gone with the 400i, and as a whole it sounds slightly more clear overall, thanks to minimal distortion and a lack of magnets on the diaphragm's ear-facing side, meaning less acoustical resonance.
 
However, even though the balance and clarity is a large step up from the HE-400, you lose some impact on the 400i's bass, and its soundstage isn't as large as the original HE-400.  Those who highly value bass impact and a spacious sound still have a reason to get the original 400, and especially these days when it can be found used for around 200usd-- a very, very good value.
 
 
Compared to its older brother, the 560, the 400i is actually very similar in overall presentation.  The 560, like the 400i, has a minor elevation in the 4-5khz region, giving it plenty of bite to make it sound energetic, but unlike the 400i, the 560 has a more balanced treble region, with more energy around 6-8khz, and less of a peak in the mid-treble at 10khz.  The lower midrange of both the 400i and 560 is excellent.  Bass of the 560 is a little bit more linear than the 400i, with the 400i showing some emphasis in the upper bass of around 200hz.  Overall the 400i is very similar to the 560, but offers less soundstage, and a slightly less refined sound due to rougher transitions from bass to mids and mids to treble.  If you can get around the colorations of the 400i, it offers around 70-80% of the performance of the 560 while being near half the price-- a damn good value.
 
 
Even though you lose some aspects to the original 400's sound, you gain so much in balance and comfort, making the 400i a stupidly good proposition for its asking price.  Complete with all the planar magnetic positives, it's a headphone a lot of people should try out if they're looking for open headphones in this price bracket.  

I am one of the lucky ones to get a chance to be reviewer in the HE-400i "tour".
 
HiFiMAN has intrigued me since the start of my Head-Fi journey. The HE-400 was the first headphone I purchased where I thought to myself "now I'm getting serious about this headphone thing".
 
Fast forward to now and a lot of money thrown at gear I have gained some experience and heard a decent amount of headphones. I am ready to give my perspective on the HE-400i.
 
Packaging:
The HE-400i is one of my favorite packages for a headphone to come in. It comes in a simple but aesthetically pleasing case and seems well protected. I did have issues pulling out the headphone initially due to the tape wrapped around (which protects the gimbals) but I understand that HiFiMAN has done their best to address packaging concerns of the past.
 
Comfort:
As an owner of the HE-560 the comfort was no shock to me. Both of HiFiMAN's latest headphones are easily the most comfortable I've ever worn. That title was held by the TH-600 previously but the weight of Fostex's cable is the difference maker. I do think my HE-400i is more comfortable than the HE-560 due to less clamp. It's just the right amount where I don't feel like it'll fall off and will never squeeze my head too much in long sessions. The HE-400i does weigh a few more grams but it's nothing I can tell.
 
Sound:
There's a lot of reviews out there that break down each part of the sound in high detail so I'm just going to write about what stands out to me. I did most of my listening with the Oppo HA-1. I did try to use it with the WA7+tp but I found the HA-1 suited this headphone a little better. I used it balanced thru the XLR with a Q-Audio cable. I'm not really on either side of the cable wars, I got it for the aesthetics and it for sure does not degrade the sound.
 
My thoughts have been made after giving these headphones a week or so of burn in time and a week straight listening of head burn in time. From there I switched back to the HE-560 for a few days then back to the HE-400. I feel like that let get more accurate thoughts on the headphone's true sound vs what I can hear when I A and B.
 
I listen to various music from hip hop, r&b, pop, kpop, classical and so on. With these headphones I was satisfied with most of my music except classical. The first thing I noticed was the small soundstage of the HE-400i. It is a very intimate sound and that sound has stayed since my first listen. It's kind of an odd feeling since vocals sounded a bit recessed to me but the rest of the audio was still in a tight space. I like the presentation for a quiet night when I'm enjoying low level listening and trying to relax. It didn't match well when I was trying to get a more energetic feel.
 
The overall sound I feel caters well to casual listeners. It has a slight veil compared to the HE-560 but that can be a good thing when you don't feel like having every detail thrown at you. I do like the overall neutral sound and speed of the HE-560 a bit more but I never felt like the HE-400i was unlistenable in comparison. 
 
Final Thoughts:
If the HE-400i was my only headphone I would be quite satisfied. It is different enough than the HE-560 to keep both but they're not that much different.
 
At $500 I think the HE-400i is an awesome value. I can't think of anything else at specific price but I would pick em over anything else in the $400-600 range.
 
At the end of the day, sound is always going to be subjective but the HE-400i will always win in comfort.
 
Don't over think, buy it! I'm purchasing my reviewer pair for sure.

So as an owner of the HE-400, I figured the 400 would be more of an update on the comfort of the model, and I was dead wrong. I find the sound signature of the 400i to be much more pleasing than the 400, but we'll get to that later. Since this is my first review, I'm gonna take the often traveled path of segmenting different portions of the review. If anyone wants pictures to accompany this, I would be happy to add them, just ask in the comments. I will be comparing the sound at times to the HE-400 with Focuspads, which do wound different than the velour pads (Better imaging, comfort, less emphasized treble, more upper mids). Most listening was done with Schiit Vali and Modi. If you don't want to read it all, there is a short summary at the end.
 
Packaging/Build Quality
The packaging of the 400i really makes one feel as if they had purchased a very expensive headphone. The cardboard-ish outer sleeve comes off to reveal a leather covered box with the Hifiman logo and slogan "innovating the art of listening" on the top. Inside the box the headphones rest in a black foam cutout, with a separate cutout for the cable and 1/4" adapter. It also has that new car smell, if you really like that kind of thing
 
Outer sleeve with images (and specs on back)

Nice box
Build quality for all pieces present are excellent. The cable is fabric-covered, and very flexible, with a right angle adapter. However, the cable is short (maybe just over a meter), which is nice for me since my amp sits about 2 feet away from me, this keeps me from having to circle the cable around the amp like I do with the 400. The headphones have a very solid construction, and are lighter than their predecessor. They are also a beautiful color. Artificial light makes them look like purple chrome, but when only natural light is shining on them, they look a very beautiful gray color. Props to Hifiman for making such an attractive and well built headphone.

All in the box

Headphones that look purple?

Or gray, depending on the light
Comfort
Initially, I actually found these headphones slightly uncomfortable, mostly because of excessive clamping pressure, however after wearing it for a very long time (worn for about 5 hours every day 12 days ago) the clamping pressure is now just right, and they have become very comfortable. They are lighter than the HE-400, and are more comfortable for long listening sessions. Comfort for the 400 with Focuspads is actually quite good, but after being worn enough, the 400i exceeds it.
 
The Sound
Now I'm gonna split the review up by the the usual method, then summarize my findings at the end
 
Bass
The usual worry for someone switching away from the 400 is whether the bass could ever be as good. Good news, I found bass on the 400i to be better. Not everyone will agree, but let me explain. The 400 has an unusually powerful wight of bass notes, but the 400i has only a tad less weight. I find it to be very close in this department. However, the ability to portray textures is beyond that of the 400, and deep bass is easier to pick up because it is less smooth than the 400's bass, in a good way. Overall I would say it is more nuanced and faster, with a similar bass weight, and more impactful, more rumbly, and what have you. If I rated the 400's bass a 9.0, the 400i's bass would be a 9.5. Not everyone agrees with this however, and I would advise looking at other's impressions as well, since other opinions are abound.
 
Mids
My favorite part of this headphone. The 400i has wonderfully intimate vocals, with airiness and texture again trumping the 400, and any other can that I've heard (though my experience is limited to HE-400, Sennheiser HD650, HD700, Momentums, and B&O H6). The vocals sound very realistic. The voices are not thinner and treble-based like the 400, and are a nice balance of mids and treble. I was unable to find a song that stayed vocally (or otherwise) sibilant on the 400i. I gained a new appreciation for vocal-centric music, like Birdy and Evanescence. Vocals aside, mids are nice and present, including guitars and string instruments. all around very clear and well textured, and one of the main reasons this headphone really outshines the 400. The extra mids and texture make electric guitars much more enjoyable as well.
 
Treble
Treble here is neutral, and doesn't do much wrong, whereas the treble was the big issue on the 400. I find the treble to be just present enough, and enjoyable. The only thing negative I have to say here is that occasionally a recording has acoustic guitars that sound just the slightest bit muted/non-resonant. Airiness in vocals is fantastic, no sibilance to be found, and all around very, very good. Lack of sibilance allows me to enjoy rap again, which is a plus as well. Treble is still present enough to enjoy with rock music (for which I find 400 and 400i about even, for different reasons)
 
Soundstage/imaging
This could be the more polarizing part of the 400i. On the 400 with focuspads, the soundstage was always very apparent at any time. With its more upfront vocals and more presence in the mids, the 400i doesn't flaunt its soundstage much. It requires a recording with intentionally distant instruments or voices to show it off. However, when these things occur, the soundstage is just a tad wider than the 400 (something I discerned after A/B with "The Angelic Welcome of Mr. Jones" by Foster the People), about equal in depth (which the focuspads increase), and a little taller. The 400i just doesn't show it off all of the time. I did find them equal in imaging, except in the case of treble based instruments, in which the 400 was more discerning of their position. Also worthy of note is the fact that before burn in or brain burn in (whatever you believe in) the vocals seemed way too upfront, to the point where it was fatiguing. After some time using and listening to them, the vocals backed off a little, but still were upfront, as I described throughout the review.
 
Overall, I believe this headphone trumps the 400 by a significant margin in every category except for bass and imaging. If you're skipping straight to this point, I advise you go back and at least read my input on soundstage and imaging. Bass of the 400i still has a slight edge over the 400, IMO, and I have to say that this headphone is really fantastic. The speed and texturing ability of the 400i is truly astounding. I wish I had an HE-500 to compare to, as it seems that the two were intended to be more similar than 400 and 400i. Vocal performance was what really got me, and I think there is a real sense of intimacy and realism in the vocals that I've never heard before. This is a very enticing headphone, and even though it costs more than the 400, it earns every penny of that.
Edit: I just wanted to add that this headphone doesn't have the biggest soundstage and isn't going to show every flaw in a recording, it is very musical in a still detailed and technically apt way. And as it seems I didn't mention any negatives, the closest thing I can find is that sometimes very busy passages can sound like they need more instrument separation or layering. But all in all, I really enjoy it.
 
P.S. ask whatever you like in the comments, I am on head-fi very often and would love to respond. If desired, I can add pictures to my review. Also, in a few days I will receive the ZMF V1 Master Model (silver rewire). If anyone would like me to compare those as well, I can do that. Thank you fellow head-fiers for your attention. Happy listening  
 

PACKAGING and Build:
The HE-400I shipped in a very nice box, with black foam insert, that holds these amazing cans in place. Also in the box was the cord and 1/4th adaptor. The did not like the cord it was stiff, a tad short, and the adaptors were a bit awkward, for my numb hands, to attach to the headphones. Once I got the cans out of the foam insert I was amazed at elegant they look and feel. 880 found these headphones to be neo-spartan, exquisitely functional, yet elegantly beautiful. The crew at HIFIMAN, using high qualities plastic resin, leather, metal and chrome have created a headphone that is light and very comfortable to wear. Although I did find the stock pads to be a touch warm, to my ears. I would sometimes puts these cans on and forget I was wearing g them, just getting lost in the the music.
SOUND:
BASS:
The bass on these headphones, was the best I have heard so far. I found the bass to be full and textured, the sub bass seemed deep and impactful. I really like the way the bass sounded playing rock like Led Zepplin or Frank Zappa. On a ranking of 1 to 10, I would give these cans a 8.
TREBLE:
The treble on the HE-400i's is very nice, after listening to these cans, I now found my Alpha dogs a touch sibilant.
SOUNDSTAGE:
I found the soundstage to be intimate. The vocals seem to right in front of you, and the instrument seemed closet together than I though a open backed set of cans. Most musical genres sounded fantastic with this sound intimate, slightly forward soundstage. However I found the instruments in classical music seemed a tad congested at times.
SUMMARY:
The folk at HIFIMAN have rally created a great headphone for the money. These cans look great, are so light and comfortable wear. And most importantly these headphones sound great. They play most musical genres well,. Vocals, either female or male, sound great, very crisp and clear.
EQUIPMENT USED:
Kenwood Multiple compact player into a pioneer Reciever, from the Reciever to my Schiit Audio Lyr 2 powered with Gold Lions.
Music used for the review:
Frank Zappa's one size fit all.
Pink Floyd's Dark Side of the Moon.
Chesky's Ultimate Demonstration Disc.
Tomita Planets.
Mozart's Oboe Concerto.
Tim Burton's Nightmare Before Christmas.
Led Zepplin's Bron-Y-Aur Stomp and Kashmir.
Henry the V.
Green Jelly Cereal Killer.
Negativeland Pepsi.
Talking Heads Stop Making Sence.
Eric Clapton Crossroads.
Dave Bruebeck.
Charles Mingus.
Thelonious Monk
The Residents The Tunes of Two Cities.

HiFiMAN HE-400i and HE-560 review & comparison - w/ stock grilles and Focus pads
 
Disclaimer: The following review/comparison is my subjective assessment of the two headphones. The differences between the two are not night and day quantity-wise, but represent a difference I was able to hear. Both headphones are great sounding devices and this review and comparison should serve to highlight or point out the differences. If you have any questions or if you want to point something out, please do let me know. Hope you enjoy the read ^_^
 
Introduction
- I received the HE-560 in early July and the 400i last Monday. When I wasn't doing critical listening or direct comparisons, both headphones were being burned-in using pink noise or playing music. Initially, I did not find them very different - it was with time, precise volume matching, listening to many different songs of various genres and most importantly lots and lots of swapping headphones, comparing short segments of different songs, movies or games. After this exhaustive process, the differences finally became clear. I am confident that these comparisons represent my current [and hopefully final] opinion on these two headphones. One thing I very much want to point out - at their respective retail prices, both headphones represent tremendous value. If I only owned one or the other, I would most certainly not find any of either headphone's relative shortcomings troublesome enough to not live with. Also, please do keep in mind my particular setup as well. I will first evaluate each headphone based on its own merits and only then compare it to the other, mentioning where the differences lie, to keep it organized and easy to navigate. Without further ado, here's the comparison.
 
Equipment:
Media: JRiver Media player 19, using ASIO KS direct connection output
Source: USB output of a desktop-PC
DAC: Audio-gd NFB-7 via USB input
Amplifier: Audio-gd SA-31SE via single-ended RCA input
Headphones: HiFiMAN HE-560 & HiFiMAN HE-400i via a 1/4 TRS plug
Files: FLAC, 128-320kbps MP3, 256kbps AAC, AC3/DTS [JRiver upmixing - movies], Dolby Headphone/ SBX Pro Studio [via external DSPs - gaming]
Cables: stock power cables, decent RCA/USB/TOSLINK cables
 
Bass
 
HE-400i
- The 400i has a very good bass response. The mid-bass has a good punch to it and is slightly emphasized, which helps with tracks where the impact is less than desired. The sub-bass is quite good too but rolls off just a bit sooner than I'd like. As far as bass definition, timbre and clarity goes, the 400i keeps a good balance of things. The slight emphasis of the mid-bass does mean that a slight portion of clarity and definition gets lost in the “punch”. It also makes certain instruments sound just a bit boomy [like a timpani or toms] at times, while also having a bit less than perfect control. The bass overall has more punch than it has extension and depth. In terms of tonality still, don't expect it to stray too far away from neutral, just a slight, enveloping bass warmth-tilt. When all's said and done, the bass is very exceptional and capable of sounding phenomenal with the flaws being pretty small.
 
HE-560
- The 560 has likewise excellent bass. The mid-bass to sub-bass transition is perfectly linear, which means the bass stays neutral, with equal presence. That means, that it will not help with any bass deficiency in recordings but nor will it add any emphasis. The sub-bass is very impressive and goes very deep, giving bass instruments a very realistic tone. Timbre, definition and clarity is as good as I've heard. The punch might be perceived as slightly softer at times, but it is for the sake of preserving all the details in the recording - any more and you'd lose a tint of definition or texture or make that instrument a bit less natural. Nonetheless, it is something to consider. All, in all, if you seek a perfectly neutral bass response that can sound terrifyingly real, this is the one.
 
Differences
- The bass of the two is more similar than different. The 400i trades a slight mid-bass emphasis for a slight loss in texture and detail, while the 560 remains equal, give or take, in all of them. The sub-bass presence and extension goes to the 560 and so does the timbre and realness, more on that later. Both can hit hard, the 400i slightly more so, and sound equally impressive with the 560 just being more tonally correct overall, with better sub-bass, while the 400i bass retains more spotlight and presence in the mid-section and upper-bass.
 
Midrange
 
HE-400i
- The 400i has a midrange that is more forward and up-front than what would be considered neutral. All instruments in the midrange always have their place, with very equal presence. Everything is very easy to distinguish, thanks to exquisite separation. This makes up for a very euphonic, bigger-than-real midrage, which ends up sounding pleasant more often than not. However, this can bring a certain shoutiness to instruments as well. For example, an instrument playing solo [say a piano or a violin], which means there's already a spotlight shining on it, and when you double that, it might just become too much, blending strikes and keys together in a slightly harsh forwardness. The upper midrange-lower treble transition is an area that is a lot less forward in comparison and can sound a bit muted in relation to the rest of the midrange, but nothing too troublesome. Overall, the midrange is more or less forward and coherent, with just a few slight dips and peaks preventing it from being completely perfect as is.
 
HE-560
- The 560 has again a very coherent sounding midrange, not forward or laid back, with just enough presence to sound true. That does mean, that some instruments [like triangles or xylophones] can blend in just a bit at times, but the midrange is in no way recessed. The good thing is there's no harshness to be heard and instrument solos sound just lovely, be it pianos or guitars. In general, the more spotlight an instrument steals in the recording, the more it will get and even as its presence increases and disappears, the instrument always appears and decays with finesse. Much like bass, the midrange is the most realistic I've heard, bringing tears in breath-taking solos or just going with the flow among other instruments, while never sounding thin and retaining good dynamics.
 
Differences
- The key difference here is obviously that the 400i midrange is more forward and just brings attention to itself and every instrument there is, thus creating a more often than not, very pleasant coloration. The 560's midrange is just there and lets the recording [or the conductor] to bring the attention to a particular instrument, or not. As a result, the 560 is more natural and delicate, while the 400i presents midrange in a more euphonic and iconic fashion. Midrange, like bass, is where both headphones are competent enough, without any significantly detracting factors.
 
Treble
 
HE-400i
- The 400i's treble is a bit more complicated. As has been pointed out, the upper midrange-lower treble region is a bit less present, or to put it more simply, the treble is there but it is slightly overshadowed by the relative forwardness of midrange and bass, while the upper treble region is more present. The treble is smooth and well extended overall, without any major peaks but it just does not carry the airy presence I like, and what I assume is the side-effect of this - a noticeable lack of air to instruments that extend to the treble and female vocals. This negatively affects their timbre and accuracy, among other things. It is still a coloration, however, that might be desirable, especially for those people who don't want much treble energy and seek just that warm-tilt with a slight upper-treble sparkle this provides. This is thus a very subjective flaw. It does not affect other things as much, but it is definitely something to consider if you want a completely even and open treble. Other than the air issue, the treble is pretty great and smooth, and if you don't need lots of air in your music, you'll certainly like it. It also varies from genre to genre and track to track, depending on many a factors. Some tracks also add an artificial layer of air to vocals - this is not what I mean. This is natural and is present in each on to a degree.
 
HE-560:
- The 560 presents treble in an effortless and convincing manner. Much like midrange, the treble is just there. It isn't harsh or deficient but always present, contributing to an airy presentation. There's no emphasis on cymbals, like the HE-6 used to make. Female vocals sound especially lovely and energetic, with just the right presence. The treble region is an area that is said to be the hardest to do right without either artificially overdoing it or making compromises and cutting back. The treble is again the best I've heard. It is not always incredibly airy [the HE-6 is more so] but it has the power to be just as and more often than not it is and certainly to a point of sounding convincing and not artificial. It always straddles the line of being too smooth and too forward and thus ends right where it should - in the middle.
 
Differences
- What separates these two trebles is more than anything, the air. The 400i treble is handled in such a way that it allows very little room for air while the 560 allows for much more. This does mostly affect the decay, timbre and just the way how real and authentic things sound. Best way to demonstrate is with an example. As voices or instruments travel through the air and eventually disappear, they leave a trail around them, a faint presence of sound and movement, what is best described as air, as well as a part of timbre or decay. This air, produced by each instrument or vocal, moves with said instrument or vocal, until it eventually disappears. On the 560, this presence is more and it rises up or moves outside of the field of said instrument/vocal as it decays, almost as if it moved beyond the boundaries of the headphone and their drivers, in a natural and convincing way. If the bow of a violin is moving from left to right and disappears, so does the airy presence. The 400i has less and does not do it nearly as convincingly - you never feel the air 'leaving' the headphone, it stays inside, trapped in the cups and just stops, with a less convincing and shorter decay. This is for me subjectively the most notable deficiency in the 400i's treble, but a very subjective thing indeed. Air is obviously not limited to treble - it manifests itself in the midrange and bass as well, but is not as apparent there as it is here.
 
Vocals
 
Male
 
HE-400i
- The 400i handles male vocals beautifully. As they are part of the “Magical Midtange”, they are put more forward than female vocals and have great body and presence. The sibilance is never an issue as there's a noticeable dip in the region where major sibilance occurs. At the same time, this dip can have a negative impact, producing vocals that sound a bit muted in the 'S' region and slightly forced in the 'T' and 'F' regions. I suspect the lack of air is partially the cause for the hardness or roughness. This is a very minor issue, however, and is rarely present and hard to focus on without a direct comparison. Still a pleasantly natural vocal performance!
 
HE-560
- The 560 does male vocals the same way it does it's midrange. No extra body or forwardness, though certainly enough to appreciate the delicacy and realistic nature, but without any extra magic. The “S” region is slightly more pronounced and as a bonus sound more natural and relaxed. The trade-off is that sibilance is more likely to show and it does - so far it was an issue with one track, which the 400i handled better. I again praise the way how vocals vanish into the air and I suspect this naturalness does take away some of the sibilance or hardness there could have been.
 
Differences
- Both headphones handle male vocals exceptionally well. The 400i takes the “more forward and smoother” approach, with more body and presence but an easier tonality on the ears, while the 560 picks the “natural and present” approach, with less body but more nuanced. Both approaches are very enjoyable.
 
Female
 
HE-400i
- The female vocals have good presence and definition. They sound quite natural and without any sibilance. There's again slight mutedness in the sibilance region, and minor emphasis on the 'T's and 'F's at times, coupled with the lack of air, and consequently realistic timbre, does hurt it a bit. That's mostly treble vocals of course, so it is specific to singers in that range. If you listen to female singers with vocals that fall to the midrange more, then those will sound even better. There's definitely noticeably more presence to midrange bound vocals. Still, midramge, or not, the 400i does very good with female vocals too, with good body and presence, eliminating any sibilance there is, unless it is brutally present. It is still a midrange monster however, so it does best there.
 
HE-560
- The 560 puts treble female vocals more forward, giving their voice more presence. Coupled with great timbre, air and decay, treble bound vocals sound energetic and beautiful. There's less compensation for sibilance, still enough for vocals to not highlight it, but not enough to mute their transition through that range.
 
Differences
- Again, air makes the most difference here, contributing to a more contoured, and realistic listen on the 560, along with slightly better resolution and finesse. Consequently, the 400i is hurt much more by it's lack of any substantial airy quality than by anything else and should we ignore the differences in air, the two are surprisingly close, with the more expensive headphone having just a more even treble response, but which is to be expected at almost twice the price.
 
Sibilance
 
HE-400i
- The 400i has absolutely no issues with sibilance. There's that slight mutedness in this range but nothing major. A great accomplishment with regards to sibilance!
 
HE-560
- The 560 fares much the same in the sibilance range. The mute is slightly less and theoretically the susceptibility is a bit higher but not enough to be an issue, and it certainly does not take away from the beauty of the vocals.
 
Differences
- Both headphones deserve praise for the way they are tuned with regards to vocals as both fight sibilance equally well. The HE-6 struggled with it at times, the AKGs do too but the new HiFiMAN set an example in the way sibilance should be tackled. On my setup, obviously. Big thank you for this, team HiFiMAN!
 
Soundstage
 
HE-400i
- The 400i has a soundstage that is definitely on the smaller, intimate size. Width is just okay, while depth is quite good and so is height. As far as soundstage expansiveness goes, it is quite average. The sounds do not feel like they are coming from outside the headphone. I also believe this directly correlates and is connected with the lack of air, and consequently openness as well. However, while the soundstage is still well-integrated and feels natural. It might feel slightly claustrophobic where there are many instruments at play, but then soundstage separation always remains excellent. Detail retrieval is good too. It also does rather well with regards to imaging!
 
HE-560
- The 560 has a moderately wide soundstage, where instruments evenly spread across believably, with good stage depth and pretty spectacular height placement, thanks to great imaging capabilities. The stage is pretty expansive, which I again believe directly correlates with the amount of air and the way it opens up the stage and gives more space and room for instruments to breathe. It still probably won't win many awards either, at least not in terms of sheer size, but it is likewise very natural feeling and well integrated. It is just big enough to allow enough room for instruments to not feel compressed and coupled with brilliant instrument separation it works pretty well. Detail retrieval is likewise great.
 
Differences
- The differences lie mostly in width and openness, where the 560 clearly has the upper hand. Instrument separation is excellent on both headphones. Imaging also goes to the 560, though the 400i also images well. The 560 and 400i both have well-defined and respectable soundstages in the world of planarmagnetic headphones but there's still some catching-up to do to rival those headphones that are renowned in this category.
 
Imaging
 
HE-400i
- The HE-400i images pretty well. It might not be the most distinct, and vocalists that are close to each might blend in just a bit, but it still does it respectably and without any major hiccups - an imaging well done, where things are still not difficult to pick up and follow.
 
HE-560
- The 560's imaging is even greater. It is very precise, with great definition and makes locating various instruments and vocals in the soundstage even easier. Very accurate!
 
Differences
- The 560 has a slight advantage here but the difference is not too big. Yes, sounds are a bit easier to locate and follow but the 400i is not too far behind and certainly not as far as the price difference would suggest. Both imaging capabilities are certainly above average and better.
 
Instrument separation
 
HE-400i
- Excellent. Separating instruments is a breeze.
 
HE-560
- Excellent. Instrument separation is an easy-peasy task.
 
Differences
- A complete tie. Maybe that guitar has a bit more presence because of the 400i's forward midrange or that female vocal is a bit more distinct on the 560 because of its more uniform treble.
Both are exceptional. Both trade blows. An honest tie.
 
Overall Sound Openness
 
HE-400i
- In case you haven't noticed already, the 400i is not a very open-sounding headphone. It tries to be and at times it sounds quite open but it has too much going against it. The lack of air, the average soundstage size and openness, the bass/midrange X treble slight discrepancy. It is warm and it sounds the part. The 400i is a closed-in headphone. It still sounds like an 'open' headphone and covering the grills still produces the same effect as on the 560 but it is certainly one of the less open sounding cans.
 
HE-560
- The 560, on the other hand, sounds pretty open. Instrumental pieces especially come to life. I've been listening to a certain piano and violin duet and the resulting emotion was simply phenomenal. Amazing leading edge on the violin, great delicacy and definition on each key as the piano played and the amount of air each made. Yep, this sounds pretty open to me.
 
Differences
- HE-400i sounds closed-in, HE-560 sounds open. I think everything that needed to be said was said.
 
Air
 
HE-400i
- The 400i has little air. There's some air to male and female vocals in the midrange but vocals located in the treble and most instruments get very little air. It's all connected with the closed-in nature of the headphone. Openness, air and timbre/realism simply suffers for it and not much can be done.
 
HE-560
- Again, the polar opposite. A lot more air to all vocals and instruments. The most impressive thing, however, is how bass instruments [NOT synthetic bass] sound. Lots of air, deep, very tight bass with perfect texture and definition. String bass is just phenomenal, but any bass produced by a real instrument is like that with these.
 
Differences:
- Same as with openness. The 560 has it in much greater quantities. Thanks to overall openness, evenly integrated treble, etc.
 
Timbre/Realism/Decay
 
HE-400i
- To me timbre, realism, decay, openness, air... all these have to work on a certain level to create a headphone that is truly open and transparent. If one of them fails, then the rest can't be too great either. The 400i unfortunately does not perform too well in either of them, including timbre and realism. I find the instruments to sound slightly artificial [string bass instruments have wrong impact/texture ratio] or colored [the midrange forwardness] and the lack of air does not allow for realistic decay either. That, however, just means that the headphone isn't truly open and transparent, not that it isn't good! It is! And again, all just directly compared to the 560. They sound quite good on their own in timbre/realism, just colored.
 
HE-560
- The 560's timbre and realism is spot on and so is decay. Instruments and vocals appear and disappear realistically. Guitars, pianos, violins, tubes, horns, double basses, ... string, key, blow, percussion... male, female... The 560 is an open and transparent headphone. And it is also pretty good.
 
Differences
- The 560 once again wins in these categories. It is the 560's strong suit but not so much for the 400i. It gives instruments and vocals an artificial tone and/or coloration. It is still quite a pleasant sound, of course! You might even enjoy it more. It still sounds good, albeit less accurate.
 
Overall Cohesiveness/Balance
 
HE-400i
- The 400i certainly has a warmer tilt. Punchy bass, forward mids, smooth treble and good musicality and dynamics. Still, it is a rather coherent-sounding headphone with good detail retrieval, great instrument separation, decent imaging and an intimate soundstage and all that has been established. It is also a suitable all-rounder. Maybe not the best pick solely for instrumental or dub-step, but it does those genres likewise reasonably well, along with pop, rock, electronic, alternative and others.
 
HE-560
- The 560 is really a neutral sounding, balanced headphone, with excellent musicality and dynamics. Great bass, midrange, treble, imaging, soundstaging, separation, detail retrieval... Well, we already know that! It wouldn't be my pick if I only listened to hip-hop, rap or dance but they also perform well with the rest. I really love it with instrumental music. An extremely cohesive performer it is.
 
Differences
- A warmly tilt headphone and a neutral headphone. Both extremely good for the price. I am the first to admit that the differences were initially rather hard to discern until I trained my ears. I could honestly live with either of them but at the same time, I am glad I have the opportunity to extensively compare these and appreciate the things they do or don't. And then choose one.
 
Low-level listening
- Both headphones perform equally well in terms of low-level listening and do not lose anything from their qualities. The quieter you listen, the more their shortcomings come out but since none of them have any that'd noticeably affect your listening experience, you can pretty much listen as loud or quiet as you want without issues. I listen at listening volumes 35 and 31/100 respectively, then 30 and 25, 25 and 20 and finally 20 and 10 and they continued to sound just the way they did when they were louder... Just quieter.
 
Build Quality
Differences
- Both headphones are built better than their predecessors, no doubt. Though, the 400i had an extra month of polish and it shows. It looks noticeably more refined and made to a tighter standard than my one month old 560. The adjustment mechanism, the clamp ratio, the ear-cups swivel, the baffle and the pads-attaching mechanism look and feel more Swiss and precise. As far as aesthetics go, I like both - the more muted look of the HE-560 and the more bold appearance of the HE-400i, but build quality wise, with my two particular pairs, the 400i edges ahead.
 
Comfort
Differences
 
- Both get a 10/10 with the Focus pads from me! Easily the most comfy headphones I've had the pleasure to wear so far. The only difference is in clamp but that comes down to consistency and not a particular model. My 560 is a bit more clampy while the 400i is a bit looser, but ultimately nothing to detract from the ultimate experience. No itchy or sore ears. No pressure points on the top of my head. Nope. Nada. None. I am also not a fan of the Focus-A pads. Sorry ^_^
Gaming
Differences
- The 400i has the slight advantage in mid-bass thump. The 560 has a better sub-bass, more precise imaging and a bigger, more natural soundstage. along with a more focused treble and a bit better detail retrieval. Neither, provide an absolutely immerssive, head-rattling experience, obviously. I'd say they both work quite well for both competitive and immersive gaming if you don't require massive amounts of bass. For me, clarity, soundstage and separation are an integral part of my gaming experience and I'd give the slight nod to the 560 for that. Also, deeper bass ^_^
Movies/Series
Differences
- Same as with games. The better extension in the sub-bass along with extra clarity everywhere else comes in handy. Swords ring, guns fire, explosions explode, dialogues play out, all with an extra layer of resolution. Admittedly, the whole experience is a bit better for me with the 560, while the 400i still holds a pretty close second. Also, you can totally tell bad acting and fake sound effects with either... Eeeew.

 
And that's it. To recap, the most notable differences are by far the openness/air/timbre related ones, while the bass/midrange/treble are more subtle. That does not mean you should think of the one as a beefed-up version of the other. No! One is significantly warmer while the other is very neutral and balanced, These differences are real, just not to the point of being obvious from the very first listen. It took quite a bit more :] And I really like them both, though I have my preference, obviously.
Thanks for the read. Hope you like it! Feel free to ask, comment or point out.
Cheers!
Luke
 
Pictures:

 

 

 

 

 

 

Intro
The HE-400i is the latest headphone from Hifiman. It was released recently as a replacement for the popular HE-400. This write-up will give my initial impressions of the HE-400i as well as compare it to its predecessor.

I received my pair straight from Hifiman for reviewing and demoing purposes, here are my unboxing pics: http://imgur.com/a/04xke

Disclaimer: the last picture shows some kind of ink or colour on my hands. I thoroughly checked the headphones, contents, box, and packaging. I couldn’t pinpoint where it came from exactly. So let’s assume it wasn’t from the unboxing.

Presentation and Build Quality
The HE-400i came packaged in a nice leather box with foam insides. A huge step up from the cardboard and cheap plastic packaging of the HE-400. The only accessories included were the cable and the 1/8 to 1/4 adaptor. The cable is of a rigid fabric material. It is generally well-built and the cable itself isn’t too rigid. Much more flexible and a tad thinner than the black Canare cable included with the original HE-400. One thing that confused me about the cable is that it is very short – around 5 feet. Another thing that confused me was that it was terminated in an angled (90 degree) jack. Why is Hifiman including a short, 90 degree angled, cable with an open headphone? This cable would make more sense for a portable closed pair. The HE-400i uses the same coaxial cable connectors as the previous generation. Personally, I’ve never had an issue with this technology but I know many despise it.

The headphones themselves are primarily made of a light plastic with some metal here and there. They simply look amazing. Beside the HE-400, they don’t look as heavy-duty or strong. But once they are handled, it becomes apparent that the construction is solid. The main chassis is made out of metal. The headband seems to be made of layered fabrics with faux leather on the outside. No issues with the stitching. The gimbal portions are a matte black plastic, in comparison to the HE-400’s metal. The cups are a shiny silver which reflects different colour tones based on the lighting. Very aesthetically pleasing, but I wouldn’t put too much faith into them staying pristine. The outer shell or paint seems weak. My unit has some scuffs and imperfections on the cups. When I asked Hifiman, they told me that my unit wasn’t “new” implying that it was pre-handled. My HE-400, on the other hand, doesn’t have that issue with the cups. The grills of the two headphones are the same.

Pads included with the HE-400i are the new FocusPads. They are loosely based on Jerg’s modified pads. Angled pads with pleather on the outside circumference and velour at the end. They look and feel better to the touch than the pleather and velour pads of the old generation headphones.

Comfort
The new headband system is a very welcome change to me. Although thin and not well padded, the headband is very comfortable as it is wide and flexible, adjusting naturally to the shape of your head. The overall weight of the HE-400i is much less than the HE-400. When worn, it feels even lighter, due to the weight distribution of the new headband. In comparison, the HE-400 headband is much more inflexible, smaller, and uncomfortable. Another issue with the HE-400 was that it wasn’t friendly with smaller heads. The clamp was not enough, and even at the smallest setting – it was too big. The HE-400i adjusts wonderfully to a large variation of head sizes. However, Hifiman overcompensated when trying to remedy the clamp issue. The clamp is now ridiculously strong. I have never felt a clamp like this in a headphone before. Pulling the cups away from each other feels like you’re prying two magnets from each other (and in a way, you are). But when actually wearing the headphones, I didn’t have an issue with the clamp. Then again I have a small-average head, and I foresee many with larger heads having issues. The FocusPads are a step up for the most part. First, the pads themselves are very spongy and feel great around your head. The fabric used for the velour portion is also very nice on the skin. Much better than the HE-400 velour material. The pads are however shallower so it is more likely that your ear will touch the drivers. The inside diameter is also smaller so your ears will be touching more of the pad. For reference, my ears slightly touch the drivers on the HE-400i and the edges of my ears touch the inside pads. But with the HE-400 with velour pads on, my ears hardly touch anything. Which is more comfortable will be up to the user. All in all, the changes in comfort are a huge improvement. Within a few minutes, it always feels like the HE-400i has disappeared on my head. I don’t think anybody has ever said that about the HE-400.

Sound
The HE-400i is a 35ohm headphone with a 93db sensitivity. Almost the same as the HE-400 and should be fairly easy to drive. I used an Objective2 amp with the Fiio E17 as my DAC. The sound signature of the HE-400i is very balanced. If I heard this headphone willy-nilly, I would’ve never have guessed that it was the predecessor of the HE-400. It sounds closer to the HE-500, but even that comparison isn’t perfect. It’s certainly not v-shaped like the HE-400. I can’t pick out which frequencies are elevated above the others. It just sounds very neutral without being boring. Going to the HE-400 from the HE-400i, I can feel sounds missing from the music. Tonality is probably what the HE-400i does best. Everything sounds so accurate and natural. Similar to the HD600, maybe a smudge warmer if anything. None of that weird timbre that the HE-400 suffers from. Speed is also very good, on par with the HE-400. As is the detailing and clarity.
 

1. Treble

Treble is great. Well extended. It doesn’t have any of the imbalances that the HE-400 treble faced. I never noticed any stridence or sibilance. The HE-400 on the other hand is known to be sibilant with certain recordings. The HE-400i’s treble has a harder texture to it, and some may not like it over the soft airy treble of the HE-400. Part of this may have to do with the fact that upper treble is emphasized over the lower treble on the HE-400.
 

1. Mids

The mids will be the biggest shock to anybody coming from the HE-400. They are no longer recessed at all. I would go as far as saying the mids are forward. Tonally, they aren’t too thick or too thin. Both male and female vocals sound impeccable. Due to the forward mids, vocal presentation is up-close and personal. It sounds like the singer is right next to your ear. Some may like this, others may not. In comparison, the HE-400’s vocals sound much more distant due to the recessed upper midrange and lower treble.
 

1. Bass

Initially, the bass is what disappointed me the most and I am still disappointed. The bass is very nicely textured and accurate for the most part. However, it lacks the impact, body, and quantity that the original HE-400 had. Subbass, although not terrible, also doesn’t extend as well as the HE-400. Some may love the accuracy and neutrality of the bass, others will find it thin and boring. One of the main thing the HE-400 had going for it was the bass. It extended very low, was linear, and was powerfully pleasing. It was unparalleled in its price class. The only headphone I’ve heard which I thought did bass better was the Audeze LCD-2 at three times the current HE-400 cost. Not sure why Hifiman would go this route with the low end, especially when they released another can, the HE-560, which is supposed to be more of a reference product. Regardless, the bass isn’t terrible but if the bass was the main reason you liked the HE-400 then purchasing the HE-400i will be a downgrade in that regard.
 

1. Soundstage & Imaging

The biggest weakness of the HE-400i is the soundstage. The headphone simply does not sound very open at all. The soundstage is small and has an in-your-head sound. Very reminiscent of the LCD-2 – but more closed it. Some may prefer the intimate, close to the ear, sound, but others will find it congested and suffocating. There is OK depth, but very little width. The HE-400 by comparison has a much bigger soundstage, it is a very open sounding headphone. Fairly wide and deep. AB-ing between the two headphones, the “openness” is the most obvious advantage you’ll hear from the HE-400. There are two things which I think are contributing to the closed soundstage of the HE-400i over the original. The first is the signature. The forward mids and overall balanced signature sounds a lot less spacious than the v-shaped signature. Secondly, the shallower FocusPads (compared to the stock velours) may be to blame for the in-your-head sound since your ears are closer to the driver. Considering the limitation in soundstage size, I think the HE-400i pulls off imaging decently. Sounds come from where they should be coming from, but compared to the HE-400, the HE-400i does not impress. The HE-400 imaging is interesting, you can hear sounds popping up from empty spaces of air all around your head. Many are a fan of this, but others will criticize it for sounding weird and praise the HE-400i for sounding more natural and coherent. Instrument separation is good as well but due to the limitation of soundstage, sound signature, and lack of air in the treble – it doesn’t sound as great as the HE-400. Frankly, the HE-400i sounds pretty compressed and not very dynamic.

Value
At $400, and later $300, the HE-400 was a great buy and has always punched above its weight. The HE-400i, at $500, can hold its own against competitors like the Sennheiser HD600, HD650, Oppo PA2, Mr. Speakers Alpha Dogs, Beyerdynamic T90, DT880, and Hifiman’s own HE-500, but it’s clearly not the obvious choice in terms of value. Consumers are more likely to purchase something with better reputation and popularity over a new product – especially if it’s priced the same. The inevitable future price-drop is what I think will drive its popularity.

Conclusion
Overall, the new HE-400i does so much right and so little wrong. It is a great all-rounder open headphone and will definitely please many audiophiles. It’s a very technically proficient headphone. What it isn’t though, is a true replacement for the HE-400. Instead of just refining the HE-400, Hifiman took all the weaknesses and overcompensated for them – and in turn killed all the attributes the HE-400 was known for. Fit kind of loose? Let’s make it clamp like crazy. Pads are too hard? Let’s give them the squishiest pads ever so your ears practically touch the driver. Upper mids and lower treble a little unbalanced? Let’s get rid of the upper treble airiness and push the mids all the way to the forefront. Now we’re left with a headphone with a small soundstage, underwhelming bass, without the airy treble, overall spacious sound, or fun v-shaped sound signature. It’s a great headphone, and I may keep my pair, but it won’t be replacing my HE-400, even if it is “better”.

TL;DR: The HE-400i is a very comfortable, very balanced, easy-to-drive, Hifiman can with OK bass and a small soundstage. Not a true sequel to the HE-400.

Note: this is my first attempt at a proper headphone review and I’d love some feedback.

Build Quality and Comfort
 
No matter how good the sound of a headphone, if you have a model that is poorly constructed or prone to break it will be difficult to enjoy and appreciate them in the long run.  Despite some problems with build quality on earlier hifiman models, there are simply no problems to report here.  I’m very appreciative of the crew at hifiman who’ve listened to the community and redesigned the 400i, making the quality, fit, and finish leagues above most offerings.  I just love the design choices here. The paint is beautiful and some of the best looking painted cups in the business.  The color is difficult to photograph, but looks much like the he4.  I call it black chrome. The suspension pad is without a fault in choice of material and fit. The adjustment of the headband comes with solid clicks and feels very secure.
 
Comfort, while previously questionable on older models, now leads the way with some of the most comfortable headphones I’ve had the pleasure to wear.  The clamp, reduced weight, and pad construction are exceptional and offer a headphone that can be worn easily for hours with no fatigue.
 
My only real complaint with the design of the headphone is the connectors. I just don’t like them, period. I know that many of you have never had problems but please appreciate that many have. There are just too many very nice single click and forget it connectors to be using these screw on type.  The cable is improved this time and with a nice insulated jacket and is more flexible.  But mine is only about six feet and I’d prefer a slightly longer cable.
 
Sound Quality
 
So now that I’ve proclaimed the 400i wonderfully redesigned and supremely comfortable, how do they sound?  I’m happy to say this this is a great sounding headphone.  There is good balance across the spectrum with that signature warm tilt of the sub bass. The bass blends well into the mids without bleeding into the vocals in any perceivable way.
 
And just what about that bass? Does it retain the wonderful extension and weight of the original he400? Well, almost. Previously the only bass that I’ve found to surpass he400 bass was the LCD 2.2 (pre-fazor). For extension, weight and texture it just doesn’t get any better than the lcd 2.2. I’ll give them a 10/10 for bass presentation in my book. The original he400 for me would rank a 9.0, while the 400i comes in at 8.0. Overall, across different  genres of music, the he400 seems to go down a little deeper and with better weight than the 400i. I’d call it a difference of about 15%. Disappointed? Don’t be. I’m certainly not. Let me explain why.
 
Other than the slight difference in sub bass, there is nothing that the 400i doesn’t trump the 400 on. The mids on the 400 are rich and tonally accurate. In fact, the only headphone that I’ve found to improve on the mids, in this price category, is the hd6x00. And the difference is surprisingly small. No tizzy, peaky treble here either. Just smooth and extended. The 400i is just a joy to listen to and does most every genre of music well. For me personally, the weak mids and peaky treble made the original 400 relegated that headphone to EDM, Dub and Chillstep. The 400i does those genres well also but now also does vocal centric music just as enjoyably. There’s a little sparkle to the treble but nothing harsh. Guitar plucks have a nice leading edge. Hi hat cymbals and drum brushwork come across clearly and naturally without getting muddy or unrefined. It’s a very good balance of sound.
 
I'll admit that I’m a poor judge of sound stage. I suppose it’s in the anatomy of my ear canals. I’ll leave this category to be judged by others who have a better appreciation for the subtle differences in this category.
 
Conclusion
 
Overall, I’m very pleased with the results with the 400i. There is enough sub bass to offer plenty of  a fun factor and enough good natural tone to the mids to be taken seriously with vocally centered music.  The goal stated by Hifiman was to voice the 400i similarly to he500. I’ll go on record and say that they accomplished that goal. Those two headphones are very similar in their voicing and overall sound signature.  This is a compelling headphone and should make a lot of waves in its price bracket against the likes of the venerable Sennheiser hd6x00 and soon the Oppo PM-2 to name just a few.  My hat is off to Fang and everyone on the Hifiman Team for an excellent product.
 

 
Miscellaneous:
 
*all testing was done through the Oppo HA-1/Normal Gain/Single ended
 
*Focus A-Pads came on this unit
 
*Grill Mod-if you put your hands over the cups while the music is playing you'll notice that the sound becomes muffled and deteriorates. Remove the grills and you'll get a nice improvement across the spectrum with this hp. Improved mids and sound stage with better air. 

The test unit has been in my hands for a week or two now and I feel it's due time to share some organized thoughts on these cans.
 
 
 
Build & Ergonomics
 
*** Readers are recommended to read Build&Ergonomics portion of my HE560 review, as HE400i shares majority of its external components with HE560, and I don’t want redundancy so HE560’s writeup will retain a portion of the physical description and my opinion on various parts of the shared physical build.
 
Cups
 
The HE400is use the tried-and-true resin plastic cups, in this case with a very high-chrome glossy finish. The resulting look is sleek and sexy, quite a juxtaposition beside the prudent and reserved look of HE560’s matte plastic / wood veneer cups.
 
Due to the chrome finish, it is hard to describe what the base colour actually is. Under normal lighting conditions it’s gunmetal grey with an extremely slight hint of cerulean blue / deep purple. Those coming from HE400s will be a lot more satisfied with how these cups show off.
 
Earpads / headband
 
The headband is the same as HE560’s; comfort-wise just perfection in my opinion, very few other headphones come close in terms of headband ergonomics.
 
The earpads that shipped with the test units are the Focus-A hybrid pads, which in my opinion is sonically superior than the Focus hybrid pads, but retaining a less perfect finish with the sewing seams. It is possible the production HE400i’s will ship with Focus pad though.
 
A quick note on comfort; the supreme ergonomics of the headband, coupled with the new earpads as well as the (relative to other planars) very light weight of the drivers, meant that the HE400i’s actually “disappeared” on my head 5 seconds after I put them on properly. I’ve not had that experience with any full-sized headphone I’ve tried in the past.
 
Cable
 
Again, same as HE560’s; a 2-metre crystalline copper / silver composite cable with fabric sleeving and ¼-inch plug. I have no qualms with it, but some may find it a tad too short.
 
 
 
Sound Quality & Characteristics
 
Treble
 
Treble is respectably extended with hardly any roll-off before 15kHz, and considerably smooth across the entire band. It still has a behaved mid-treble sparkle reminiscent of HE500’s treble, though is not as utterly smooth/grain-less as HE560’s treble performance. Resolution / microdetail extraction is a hair better than HE500s (mostly due to the better extension), but again falls short to HE560 by a significant margin. Since the driver assembly components are from the same pedigree as HE400’s, one might expect vestiges of HE400 treble showing through HE400i; but nope, I try to but hear absolutely nothing that reminds me of HE400’s treble issues. In the simpliest description, HE400i’s treble is smooth, very well-extended, with just a hint of extra sparkle.
 
Midrange
Midrange is very natural-sounding, and just a touch intimate. To put it in perspective with other Hifiman’s offerings I’m familiar with, HE400i’s mids are cleaner than HE500’s, but quite similar in intimacy; it (400i’s mids) is much, MUCH fuller sounding than HE400’s, and noticeably so vs. The HE560s too. Vocal/rock/solo instrumental listeners will love these mids, while orchestral/concert/soundtrack peeps might find it a bit too “familiar” and homely to be perfect. Again, I need to stress that these do sound less lush than HE500’s mids, so I’m talking fairly line-straddling differences.
 
Bass
Bass is tight/dynamic yet enveloping at the same time, which is a very interesting combination reminiscent of LCD2’s perceive bass behaviour. It is indeed slightly elevated, so those seeking a sound signature fit for bassy genres will find the tone perfect for that. Bass articulation/texture is excellent, which coupled with the slight bass elevation means all the low frequency detail is delivered in an effortless manner. I think that it offers comparable pros/cons relative to HE560’s bass, and is easily one of my favourite bass responses.
 
Clarity/Transparency
 
With regards to clarity and transparency, I think these strike as close to the mark as anything I’ve heard that tries to retain some intimacy and warmth, while keeping optimal clarity. That said, I will state that the “openness” of the sound (subjective perceived sense of how non-headphone-y, and speaker/real-life-like, the headphone delivers music) of these is not exceptional, it is about on par with HE500, but is a ways behind HE400’s openness, and nowhere near how open HE560s are able to sound. Instead of sheer openness, HE400i instead presents music in an enveloping, lounge-y manner, which in a peculiar way does sound quite appealing or even euphonic, especially with the right genres.
 
Soundstage
 
Soundstage of HE400i is decent but not exceptional; I am not a great judge of soundstage but these sound to be slightly narrower in width but deeper forward than HE500’s soundstage dimensions. Imaging is good, very similar to HE400’s imaging capabilities, though centre imaging is somewhat fuzzy / spread out across the front. If there is one thing that I find a bit weak in HE400i’s sonic repertoire, it is the soundstage/imaging capabilities. Most people will be satisfied though, just not those seeking ultimate monsters in these traits at $500 category.
 
Try out the regrilling mod for a welcoming improvement to the soundstage openness.
 
Timbre
 
HE400i’s timbre reminds me of modded HE500s a lot, with naturalness is the main descriptor. However HE400i does not stray too far into lushness/warmness, so the timbre with most instrumental stuff is musical but still considerably realistic. That seems to be the theme of HE400i, that it straddles the line between a warm/musical signature and a measured/neutral one. I do feel that fully modded HE500s have slightly more realistic vocal timbre than HE400i, while on instruments HE400i edges out due to its treble advantage. HE560 is on another level though with regards to timbre / believability.
 
 
 
Conclusion
 
In one fell swoop, Hifiman wants to have HE400i replace HE400 and HE500 at the same time, and I feel that it is indeed up to that task. Those familiar with HE400 will certainly welcome the much more even and natural sound of HE400i, while HE500 folks may come to appreciate the improvement in speed and tightness. On top of that, the ergonomics of the new line of Hifimans make this generational change all the more deserving of attention.
 
Of course, HE400is don’t quite excel in every domain compared to higher “tiered” cans, especially vs. HE560 which I compared extensively. But what HE400i does have is well-roundedness; it makes smart compromises in almost every aspect of its sound signature to bring out both musicality and technicality, which many will probably find to be extremely appealing.