The Terrific HiFiMAN HE400S Planar Magnetic Headphones

In 1995, for Sennheiser's 50th anniversary, they produced the Sennheiser HD 580 Jubilee, which became the HD 600 introduced in 1997. And ever since, along with the 2003 introduction of the HD 650, these headphones have held a position of near reverence by headphone enthusiast—many of whom will claim they remain the pinnacle of price/performance value.

I, too, hold this this opinion. The HiFiMAN HE400S ($299), in my opinion, now claims this spot.

The HE400S is a full-size, circumaural (around the ear), open, planar magnetic headphone. Now sporting the new HiFiMAN headband and angled earpads that first appeared on the HE560 and HE400i, and the 2.5mm mini-jacks on the earcups that first appeared on their flagship HE1000, I find the HE400S a significant ergonomic improvement over previous models.

The large circular earpads provide ample room for my ears and are easily comfortable enough for long listening sessions. But the overall fit leave just a little to be desired relative to the most comfortable headphones—the feeling for me was a just a bit insecure, and a small amount of manual adjustment (tilting and moving the earpieces forward and back) is needed to optimize fit. I'm nit-picking here, comparing these cans to the very best I've experienced. I would say at it's price and category, the comfort level is quite high.

Adding to the comfort is the light weight of the headphones. The HE400S is 346 grams; Mr. Speakers Ether, which is considered a very light planar magnetic is 367 grams; HiFiMAN HE1000, 493 grams; and LCD-3 556 grams. I consider the HE400S a very light weight headphone for a planar magnetic. For comparison, the Sennheiser HD 600, a dynamic headphone, is 251 grams.

The styling of the HE400S is nothing to get too excited about; it's pretty plain Jane. The headband pad is a low grade pleather; other than the headband arch and grills the visible materials are plastic. Fit and finish are quite good however; I found no creaking or squeaking in the joints or headband adjustments. Considering the price and sonic performance I find the styling a non-issue. People won't be buying these for their looks, nor should they.

Accessories are sparse...heck, almost non-existant. You get the headphones, their five foot cable terminated in a 90 degree angle mini-plug, and a 3.5mm to 1/4" adapter. No travel pouch; no smartphone cable with remote; no fancy presentation case. The cardboard packaging with foam cut-outs for the headphones, however, is well designed to act as plane but functional storage case. Meh, who cares when you're talking about a headphone designed for indoor use that's a friggen sonic bargain.

Flip the page and we'll talk about that!


COMMENTS's picture

Thanks for the review, completely agree.

Any chance you will be reviewing the 400i? Seems it's the sweetest upper mid-fi thing these days, and the sub-bass is all there. Sure the 400S will be a huge hit, but still I wonder what you think of a planar that costs more but sounds like a planar.

If not, why don't you like them? Too bright for your taste? :-)

logscool's picture

My guess looking at the measurements would be that while they do improve low bass and sub bass and distortion in that area they are missing the gentle rise in the 500-2k region and the treble energy in the 5k-10k region is a bit hot. Haven't heard either of these phones though so I can't say if that is true or not.'s picture

Using 400i for several months, they definitely dethrone 600 and 650 in sound detail, a bit off with the signature but overall great. Soundstage, however, is of a closed headphone, which sucks.

But TBH while 400S is a price/performance monster, these are just better without the "bargain" part. This is all IMO, wonder what Tyll thinks.

funkmeister's picture

Most planar headphones are a bit off tonally. Almost all exhibit the same sonic wall issue around 4kHz that is inherent in the design.

ManiaC's picture

But Tyll I want to know what you think (sonically) about HE-400i?


logscool's picture

Any chance you will add measurements with the focus pads? I know there are measurements over at SBAF but I would love to see some done on your system as well.

Tyll Hertsens's picture
I'll try to get some for measurements.
Argyris's picture

Wow. These look fantastic. After having taken a bit of a break from the headphone hobby for a while (mostly just enjoying my music with the cans I already have), just when I thought I was out, you pull me back in with this review. Off and on I've casually considered picking up an open headphone with this kind of signature to complement my DT880, but up until now all the usual suspects have been either too expensive or else had a few commonly-mentioned flaws that made them less than desirable, so I haven't really been seriously looking. This is the first time I've been excited about a headphone in quite a while.

Thanks for the write up, Tyll! As always, it's well-written and gives me a great picture of what to expect from this headphone.

xp9433's picture

I notice the measured impulse response shows a negative absolute polarity. Are the HE400s' wired out of absolute phase or this meaurement result caused by the amplifier used for the test having negative absolute polarity?

It raises questions for reviewing if it is the HPs that are wired with negative AP because used in your normal listening system the treble splashiness and weaker bass might be ameliorated by changing listening system absolute polarity/phase? Have you looked at, and tested for this?

I noticed the same for your measurements of the Stax headphones in your Big Sound 2015 exercise. Bob Katz talked aboout playing with absolute phase on his day two - did you?


zobel's picture

It could be the reason these are wired in reverse phase is that they sound better that way. The transients may be cleaner and better controlled with the diaphragm moving in that initial direction. This can sometimes be true with loudspeakers, and can be worth experimenting with on your system.

Tyll Hertsens's picture
My sense is there's a very small difference sometimes with absolute phase...but most times not. It's a simple thing though, so I don't understand it when a manufacturer wires it out of polarity.
xp9433's picture

Tyll, I will agree that listeners' sensitivity to correct (or not) absolute polarity vary. But not agree about the lack of importance of having correct "system" absolute polarity set-up in a review system.

I have been associated with correct system "AP" setup for over 25 years (and had it included in pre-amplifiers that I was associated in manufacturing way back then). It may seem a small thing for some people but to me it is that last important few % of fidelity (i.e. when "AP" is correct) that separates the great from the very good. I can't be without it!

I always therefore have bought products that allow me to easily switch "AP" when listening. For example most of my casual, work, bed-time listening is through a iFi ISD Micro that has an external "AP" switch. I have little trouble consistently prefering one or the other "AP" position for individual tracks over the reverse "AP" on about 95% of all music (the other 5% is so badly recorded it is hard to tell). AP will vary from album to album, sometimes track to track within the same album!

Now my submission is that if two products with different "AP" output are reviewed in the same (or similar) systems, the product with the incorrect "AP" will be at a disadvantage when the reviewers is using his/her favourite test records. Why?

1. My experience is that most of the reviewers's favourite recordings will have coincidentally been recorded with the same absolute polarity (It changes dependng on the original recording electroncics and system setup - about 55% positive "AP" and 45% negative "AP" output in my experience). This is because correct "AP" does have an audible benefit and whether deliberate or not reviewers will gravitate towards their best recordings. The ones that sound best in their "system". As I said, in most cases these records will coincidentally be recorded with the same "AP". So whether they are aware of it or not, reviewers are probably making decisions about correct "AP".

2. When any review item with the opposite "AP" output to the item it is replacing is inserted into a review system (that has been carefully set up over a long period of time) the very audible affects of that disadvantage will be heard, and usually that product will be blamed - not the faulty system set-up!

Those disadvantages include splashier high frequencies and sibilance, shortened soundstage depth and width with, for example, the lead singer disappearing back into the mix losing both clarity, focus, and naturalness. When system "AP" is correct the singers with come forward in the mix with greater focus and naturalness. When AP is wrong, dynamics will be blunted right across the frequency range. Basically, the correct "AP" will just sound more musically "right" and "alive".

Now here is my kicker. Reviewers train themselves to pick up small but important differences in SQ. IMO, all reviewers should work and train themselves to identify SQ changes from correct and incorrect absolute polarity, because the differences are much more than "very small", IME, and more than any reviewer should miss when trying to ensure the most accurate review of any audio product.

How can a truly accurate review be obtained if the system set-up disadvantages one product over another? The truth appears to be that many reviewers just don't bother to identify incorrect "AP" - usually because they do not have an easy-to-use or well-implemented way of switching absolute polarity, and therefore this important aspect of reviewing is missed.

With the type of headphone reference system (and with the best musical material you have), and with the appropriate pre-experimentation, I would be shocked if you, or any experienced reviewer, couldn't pick the differences in switching between correct "AP" and incorrect "AP" in such a reference system - 100% of time.

If my contention is correct, how can any reviewer not ensure that their system is set-up correctly to give all products entering it an even chance of achieving the best SQ output possible.


PS: I can't understand either why a HP manufacture would wire their HP's with negative "AP" either. However, for electronics it could be as simple as how many gain stages the product has that determines the absolute polarity output. Some products with extra gain boost stages (common in headphone amps) will change the absolute polarity when a different gain stage is used.

zobel's picture

I think this article pretty much nails this AP issue. Have you seem this?
Cheers , zobel

xp9433's picture

I don't think this is the place to get into a full and long discourse on the subject. A better idea is find a copy the the definitive publication on the subject "The Wood Effect" by Clark Johnsen. This article might help a little

A pre-requisite for hearing the SQ impact of incorrect absolute polarity is having a phase coherent loudspeaker system. An essential starting point, is having all drivers in that loud speaker connected with the same polarity (this is not the case for many speaker designs).

Most HP's have only one driver so phase coherence is not a problem. If you have an HP amplication system with a convenient and easy-to-use absolute polarity switch (physical switch is best), then "instant" switching back and forth while the music is playing will soon identify the SQ differences between correct and incorrect AP setting for that recording - especially once you know what to listen for, and have completed appropriate experimentation/training. I could go into this much deeper, but as I said this is not the place.

I was making a point that audio reviewers should have researched this thoroughly. If they had then they would always make sure that AP was accounted for properly when reviewing new equipment.


zobel's picture

I like the idea of being able to "instantly" switch back and fourth between whatever it is you are comparing in audio tests. I think it is much easier to hear differences that way, rather than with any delay between samples. It would be interesting to hear how these cans sound when switched instantly between "correct" and "reversed" absolute phase.

zobel's picture

It wouldn't be interesting at all to me how these sound under any conditions, since they are too small for me. Headphones aren't "one size fits all", so it would be good for a reviewer to mention the size of the cans. If they don't fit, they are worthless, as is the rest of the review.

Akmax57's picture

So, Tyll, I like to listen to music through headphones while my wife watches her TV shows, but we are still maybe just 3' apart. I also like to listen to music in bed after she has fallen asleep. At moderate volumes, will she be able to hear much sound? If so, what would you recommend in the same price range that would provide enough isolation for her not to hear any sound?

jhwalker's picture

Not Tyll ;) but I have HiFiMan HE-500s, which are similar in design, and they leak like a sieve :/ Virtually the same sound that is projecting into your ears is also projecting out into the room - if I turn up my headphones to the level I like to listen, my partner can no longer even hear the TV (and, likewise, you will hear every noise in the room).

So not really good for this purpose.

tinyman392's picture

These are completely open back and offer no forms of isolation (either direction). Depending on what "moderate" volume is, these will either leak too much or just enough to not bother your wife. Also, isolation will also be poor with these (for when the wife watches television). I actually would push you to a semi-closed or fully-closed headphone for what you want to do, but that's just me. Maybe Tyll will have something different to say.

Tyll Hertsens's picture
You guys covered it...she'll be able to hear your music easily. Check out the Wall of Fame sealed headphones for suggestions.
zobel's picture

My ears are 3+1/8". The recommended pads just 2+1/8" inside diameter. I'll stick with the Sennheisers.

potterpastor's picture

I have HD 600, 650, and 598. But I bought the 400S a few weeks ago. I put them on my head and played some songs and right away I said "Wow, these headphones are so clear and spacious!" I like them with my Fiio e12 more than my HD 600/650 with my Valhalla 2. I was shocked.

But the 400S doesnt mate well with the Valhalla, even when the gain is down. I get some distortion. It's much better with the e12. I guess low impedence planars and tubes don't mix?

Great review, I totally concur.

superjawes's picture's Valhalla that's the problem. The design inside that amp (all tubes) is focused on delivering lots of power into high impedance 'phones, but it has almost nothing for low impedance models.

There are tube amps that can deliver power into low impedance cans. Lyr, for example, is a tube hybrid (tubes and transistors), and it has plenty of power for almost every headphone..

money4me247's picture

I totally agree with your impressions :)

Hope it is okay to provide a link for those looking for some additional thoughts on these excellent headphones.

I posted a head-fi review of the HE-400S is here.

Direct Comparisons:

zobel's picture

I found these dimensions of some circumaural ear pads at this site:

I'm not a basshead, but this is important info for those of us that need bigger openings in the pads. I can wear the senn HD 600s comfortably, but the HD 380 Pro are even more comfortable.

I'm not a fan of round ear pads. Oval is a better design as it is way more ear shaped.

Hope this helps those with larger ears.

potterpastor's picture

Hi Tyll. You recommend the Bottlehead Crack as a good pairing with the HD 600. Which solid-state amp would you recommend as a good pairing with the HE400 S?

Tyll Hertsens's picture
Pretty much anything that sounds good. Heck, you can drive these with a phone. Be hard to point to one best amp. I'll just throw the JDS Labs Element out as a reasonable companion.
dAd's picture

Thanks for the review and measurments Tyll. I do think these cans get the most important midrange very right. And being planars they do a great job with note definition and speed.

While I have also purchased the 400s along with the Focus A pads, I have not installed them yet. I am still getting a feel for the normal velours. However, I did get a chance to hear the Focus A pads with the 400s on another rig and there was no lack of bass down low. Comparing the 400s to my Mad Dogs I do not get the bass impact with the standard 400s, but gain a whole heck of lot of less glare, more openness, higher midrange clarity and resolution and treble that is clean and nicely balanced. I can hear just a touch of splashiness up too, but nowhere near as much as many other cans. And the splash for me is ameliorated a bit due to the amp pairing. I use a Schiit Asgard 2 with the 400s and the match is quite nice.

I have owned a bunch of mid priced headphone and these are the best with the least faults for me. My 67.5mm ears fit into the round pads as they did (albeit with a slight squish) with the Alpha pads on the Dogs.

The only improvements for me would be a longer (8 foot perhaps) cable so you do not have to sit right next to your amp and a 1/4 inch plug. I hate adapters, they impact sound and these really are not a portable on the go can, so what's with the 1/8 in and adapter?

Aside from that and the slightly downscale materials as Tyll pointed out, I do not think one can get much more satisfaction without going all the way up to the $1k range.

Well done HifiMan.

veggieboy2001's picture

I don't have a lot of amps, but what I have pairs well with the 400s...I think they should be easy to pair (although I'd love to hear what Tyll thinks as well!!) as far as the cable, I thought you'd like to know that HiFi-Man offers an "upgraded" cable (hybrid OFC)...I guess it's supposed to be sonically superior. as far as replacement cords go, these seem to be a "decent" value ranging from $70 for 1.5 meters to $130 more ($200) for 8 Meters. I can't vouch for the sound as I haven't heard's a link:

dAd's picture

the linked cable is the exact same one that comes with the 400S only available in longer lengths. I guess it is pretty neat to get a $70 cable with a $300 can.