Mike Piskor 2015

Hifiman HE400s Review

Sound Impressions


This is one very neutral but smooth sounding headphone for the price. For old school first gen HE400 users this is not a return to that bass-laden but slightly uneven HE400 sound signature, but nor is it quite as rich and euphoric with a mid-bass bias HE400i. This is a different ‘HE400’ to either previous units and in many respects, at least tonally, something you could term as a new sound from Hifiman.

Clarity is excellent actually. This is a very clean presentation with a tight and fast response though not quite on the level of the HE560. For my ears the HE560 is still absolutely the more resolving and refined headphone.

For those jumping in at $299 though they might prefer the slightly more forgiving top-end response of the HE400S which is not quite as peaky as the HE560 in terms of amping though it does have one or two minor kinks in the FQ above 7k.


The most controversial of topics when we evoke the HE400 name. Yes, the HE400S is not the bass monster some had hoped for but that’s ok actually because its plus points are in some areas the older HE400 just plain sucked at. The most noticeable aspect of the HE400S is the lower sub-bass roll-off beyond the 100hz level.

Some charts have the roll-off as pretty drastic but the subjective listening experience doesn’t feel that way. There is a mild mid-bass fullness that somewhat disguises the roll off so on most genres you can still apply a bit of oomph where required, it is just not earth-shattering in terms of extension and body. Certainly, there is no loss of coherence in the sound signature overall from having a less than commanding slam factor and for me it stays reasonably balanced.


A part of this can be attributed to the single drive design (efficiency and weight a plus) and another factor is the use of velour pads which are porous in nature letting a lot of potential slam leak out before it ever hits the ears.

Shift these babies to Focus Pads and you get a slightly enhanced bass extension and oomph with a trade-off on a slightly less open soundstage but some might actually see that as a worthy exchange. I was also only able to get a limited amount of EQ adjustment with the velour stock pads using Foobar’s 18-band equalizer, particularly in targeting the 55-110hz area.

When pushed too high things started to distort reasonably quickly so I suggest the pad change is a better option if you want to enhance the slam.



mikeSmoothness is prime in this headphone’s bass experience and I found myself just kicking back and relaxing for hours. The HE400S is headphone lacks that harsh, deep reaching Planar bass of all of its brothers and there is a clear difference in texture and authority between the HE4, HE5/LE, 400, 500 and 6 versus the new age 400i and the 560i.

The latter and newer gen models are smoother, don’t extend as deep and do not feel weighted with a great solidity factor. With that in mind, the best way to describe what is offered on the low end is that the 400S sounds like a very good dynamic driver.

It feels just like the Philips Fidelio X2 in terms of texture and broadness. It is softer on impact, less firm and lacking a blaring sense that pretty much all the original HE-series models had, as well as Audeze LCD series and the Dog generation from MrSpeakers.

Now, that isn’t a bad thing, as mentioned. It just means the HE400S isn’t the right headphone for you if you want an improved HE400 low end without sacrificing quantity and solidity. However, it is for you if you want clarity that is somewhere between the original HE400 and the HE500, something that retains excellent smoothness and still is abundant in quantity.


mikeVery nice quality, forward and plentiful mids and to date, this is by far my favorite sounding Hifiman for vocals. Side by side with my MrSpeakers Ether, the HE400S sounds noticeably larger and sexier with the perceived size of all of the midrange: vocals absolutely sound larger than the Ether, as well as all the other Hifiman headphones before it.

Next to my HE500, the HE400S again sounds larger in the midrange when someone speaks or sings. Very cool! This headphone makes for a fantastic vocalist lovers experience without many flaws to even consider.

Vocals appear unlike some of the other planars out there near this price range, for example the Alpha Dog from MrSpeakers, which is a headphone that feels more solid and weighted, offering more authority to the vocal experience in a more realistic manner. I call that factor “solidity”.

In the case of the HE400S midrange, much like the low end of the headphone, it is lacking a sense of authority that I find to come stock with pretty much all Planars to date. Side by side with my Philips X2, the HE400S once again sounds similar in authority (that weighted appeal) and it is not what anyone would expect of a Planar. Summed up, the HE400S sounds like a very good dynamic headphone despite being of Planar Magnetic driver design.


I actually found the strong point of the HE400S to be the mids for me and a continuance of the slightly forward sounding mid-bass from 100hz right up to around 1k and the all-important vocal presence performance.

I am a lucky guy of late getting a lot of stellar vocal performing gear such as the VE Stage 5 CIEM. The HE400S, though not quite as expensive or resolving, really treats vocals with a far better degree of enthusiasm and focus than the older HE400 gen 1.

This is a spacious mid-range that is smooth and flowing without any hint of unevenness. As Mike states though the vocal doesn’t sound quite as full-bodied or euphoric as say the HE400i but I still felt it was a real pleasure to listen to for lengthy sessions and in no way got lost in the mix.

On some mixes such as Pentatonix, I actually preferred the energy and musicality of the vocal presence to the HE4000i. After all, Pentatonix is all about the vocals and though the HE400i had the refinement and fullness the HE400S had better energy and engagement.

Timbre on the HE400S is also pretty good though not quite on the level of say the HD600, which has a similar type of presentation, but certainly more pleasing than I expected.


mikeThe top end of this headphone feels like a cross between the HE400 originals quantity, but with the more reserved physicality of the HE300 dynamic driver that Hifiman put out a while back.

What I mean by that is that the HE400 was a bit bright on the treble and at times sharp, the HE300 (a dynamic driver) had a similar impact level, as well as a solidity factor that was perhaps a bit smoother from the HE400 original. The HE400S upper regions feel like a fusion of those two models up top. There is quite a difference again in that tonal authority that the headphone offers up there.

No doubt, my HE400, and HE500 both sound much more firm and tight, but they are also more piercing while offering a good sense of that weighted appeal that I find so tasty in Planars.

Is it a bad thing? Not at all, it is still plenty clean and clear, enjoyable and engaging. I think a lot of consumers are more used to this type of a treble and I am happy to see such a nice smoothness factor occurring on the HE400S’ treble. I

quite like it, coming off the older HE-series, I think this is actually an improvement in musicality and enjoyability and I find the HE400S so much easier to listen to for extended periods of time, despite it being just a little bright to my ears.


Treble on the HE400S is just right for me for non-critical and fun listening. It doesn’t have the biggest extension but clarity levels are good and certainly airier than the PM-3. There is a mild dip around 5k which keeps the lower treble in check particularly with percussion and cymbal work meaning the vast majority of the treble performance you immediately hear sounds relatively smooth and easy-going. Nothing too sharp here and that’s just how I like my casual listening.

The upper treble is a bit more forward around the 7-8k range with a bit of a peak, but once again subjectively I didn’t feel it get as tizzy as much as I thought it might. Only rarely on synth-laden lossy metal tracks with very heavy high hat work did it ever come across as bright or peaky.

What I did find was that the treble response did become more of matching to source or amping question rather than any inherent failing from the HE400S. Tube set-ups such as the CDM from ALO Audio were much more adept at producing a smoother treble response in the HE400S than far cooler or very neutral sources such as the FiiO X3ii.


mikeWow, Hifiman has really upgraded the sound stage experience. There is no doubt this is the most spacious Hifiman to date (excluding the HE1000). I’ve owned every Hifiman over-ear except the 400i and I can safely say it is not only the most mid-forward but also the vastest sounding.

It has a great center image presentation, which was always a problem for Hifiman in the past. In my opinion, at least, all past models had issues with imaging and required a crossfeed EQ to be enabled to obtain a more complete imaging experience, Hifiman was always kind of “stereo left, stereo right” to me, maybe I am in the minority on that?

The experience doesn’t extend far left and right, but what is now offered is an improved, more well formed imaging experience as a whole. To me, the original HE-series weren’t passable with stereo width factor, but now and on the HE400S I can consider it acceptable and enjoyable as well. Depth of field is noticeably improved over the HE400 and there is certainly a darker feel to the backdrop as well.


I actually thought the HE400S soundstage was well above average and not what I was expecting at all. It has got a great sense of airy spaciousness, particularly in the midrange. Imaging, whilst not a huge strength, is certainly more three dimensional than the PM-3 from Oppo.

Mike is correct this is not a left and right experience but there is, however, good width. Height and depth for me though are a bit more curtailed. The roll-off on the sub-bass limited any sense of real depth in the sound stage compared to the HE400i.

The treble height, though much better, didn’t quite have that airy articulation you would find in say the HD600. That full sounding mid-bass response though keeps things rumbling along at an acceptable pace.


This is the other big calling card and the reason for the “S” in the HE400S is sensitivity. It is by far Hifiman’s least demanding orthodynamic headphone in the market right now at 98db SNR and 22 ohms. This is built to play on just about any DAP and well-made smartphone. Whilst it still doesn’t quite lick the Oppo PM-3, which actually is even easier to drive at 102db, it is really not that far behind at all in day to day use.


By way of generic comparison, both of them jacked out of my BB Passport performed rather well but at slightly different gain levels. This is probably the weakest amp I have in my arsenal of amps. The PM-3 sat comfortably at around 8-8.5/10 on the Passport volume whilst the HE400S required a little more juice than the PM-3 to sound equally at home with a gain marker of 9.5/10.

The very fact I can stick a Hifiman planar into a smartphone and get very good sound indeed is a far cry from the days of nuclear power plant shopping for the HE4-6 a few years back. However, it’s still not the king of efficiency just yet. The PM-3 is still slightly ahead.

Efficiency is not everything

Having said all that I actually felt the HE400S sounded better on lower amping than the PM-3. I had remarked in my PM-3 review, the PM-3 response tends to sound a bit flatter on lower-powered amps and compared to the HE400S it didn’t feel as dynamic or engaging. So whilst the PM-3 is the efficiency king it’s not the best sounding out of the two when voltage is at its weakest.

Overall though the HE400S has a bit more to offer with a higher quality amp. Though it runs great on a smartphone, a small portable amp, particularly ones with tubes, made a tangible difference. The humble but no less capable FiiO Q1, with its bass boost options, offered a more planted and weightier bass response for example. Those opting for a simple budget stack might well want to try that combo.

On the complete opposite end of the spectrum, the CDM from ALO Audio and all that tube goodness yield a very smooth top end response than the budget amps could not offer. Personally I think that’s the law of diminishing returns right there and the HE400S paired with an E12, Q1, a Picollo up to say a VorzAmp Duo will have more than enough power and have a very nice tonal match also. You do not have to break the bank to get the HE400S singing.

HE400S vs Oppo PM-3

This is the elephant in the room as far as I am concerned and they both overlap quite heavily in terms of pitch. Both are efficiency kings, with the PM-3 being slightly louder on weaker amps but sounding tonally weaker than the HE400S.

However the PM-3 has a more premium build, is about 30g lighter and feels more robust. It is also an on-ear headphone compared to the full-size HE400S and as such you could term it as more portable.

The biggest difference for me though is quite simple. The PM-3 is a closed planar and the HE400S is an open planar and that brings a bit of chalk and cheese into the equation. The PM-3 is flatter and a bit more neutral sounding than the HE400S with a less forward midrange but a heavier and better-defined bass response amped or otherwise.

It also has a much smaller and intimate soundstage given that it’s a closed headphone. In turn, the open HE400S has an airier presentation, a better vocal presence, and a much more expansive midrange. Both are very comfortable actually but the slightly lower profile headband system of the PM-3 and thicker leather pads get my vote for short term listening outdoors. For longer indoor sessions the HE400S velour heats up a lot less and is definitely more comfortable.


Critically for many the PM-3 retails at $399 and the HE400S for $299. That $100 difference can get you a good IC and a FiiO Q1 or a FiiO X1 and you can rock out with the HE400S right away just like Mike.

Yet in all this, I am not sure if you should be thinking PM-3 vs HE400S. Whilst the big ticket is the efficiency war the questions posed are the same old questions – Open or closed? On-ear or over the ear? Great mids or better bass definition? I don’t think efficiency or planar should come into the equation if it is down to these two.

If you are out and about grab a PM-3 if you are in the office or at home with a modest set-up grab a HE400S. Do you love vocals? Get the HE400S. Do you prefer isolation and thicker bass? Get the PM-3. The usual questions still apply.

Our Verdict

I get a feeling of that’s all folks’ in terms of how far Hifiman can push the HE series both downwards in price and upwards in efficiency. There are only so many magnets you can loose in a planar before you simply have two empty cups and a string. The concept of the all-new dynamic Edition S at $199 would seem to confirm that. These headphones are still in early development and will hopefully launch by the end of the year, but a date has not yet been set.

That being said I do not consider the HE400S to be a budget version of the HE400i or a correction on the older HE400. In fact, it is priced just right at $299 for me personally and brings to the table a really easy to like sound that does very well indeed with vocals.

The fact it sounds great off my smartphone and reacts quite nicely to a small amount of portable amping is a huge bonus and compared to the PM-3 it seems a better performer on weaker amps. If you are the indoors type and want an open planar with limited amping this is a more solid choice than the PM-3 though far less portable in my mind and less suitable for those modern bass-heavy genres, leave that to Oppo.


mikeHifiman made a good new headphone in the HE400S, but it doesn’t feel like it belongs in the family of the HE-series. It sounds thinner and much more smooth, more balanced and yummy with its lack of impact; no doubt it is unique. But, it just might be that uniqueness that gets Hifiman’s name out to the general consumers and public market outside of us nutty audiophiles. I really enjoyed this headphone and I think most users who are looking for a smoother sounding Planar will enjoy it as well. Thank you for the opportunity to review this headphone, Hifiman!


HE400s Technical Specifications

  • Frequency Response: 20Hz – 35KHz
  • Sensitivity : 98dB
  • Impedance: 22 Ohms
  • Weight: 350g
  • Cable Length: 1.5 m
  • Plug: 3.5mm/6.35m

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