Drop X HiFiMAN HE-X4

This is the place to discuss all things HE-X4.

I’ve had the opportunity to spend some time with Drop’s latest entry level budget planar, the HE-X4 after having done a full review of HiFiMAN’s latest release, the HE400se. The following will be a reference point for all the measurements I’ve done on it and my findings so far.

Drop X HiFiMAN HE-X4 Frequency Response:

So, this should look super familiar to anyone who’s seen measurements of the recent HiFiMAN HE400se. That’s because they sound essentially the same. Now, it turns out that they are in fact NOT using the same drivers - at least for the international version of the HE400se. But interestingly enough, the transducer difference doesn’t seem to matter for these headphones in particular.

As mentioned, that’s close enough to where you could imagine it being L/R of the same headphone, with any slight differences being down to channel or positional variation - but these are actually two different headphones.

Now I should explain that I was also initially under the assumption that the HE-X4 and the HE400se were the same headphone acoustically because the drivers physically look nearly identical, all the way down to the glue on the magnets being the same pinkish color.



Pretty similar, right? You can see why I initially made this assumption. But if you look closely, you can see that on the HE400se, the magnet bars are rounded on the edges, while the HE-X4’s are not. This is HiFiMAN’s ‘stealth magnet’ tech in practice on the HE400se.

You can see it even more clearly when taking the grille off the back of the housing and holding them side by side. Incidentally, both headphones use double-sided magnet arrays for their design, but make no mistake, this is only one parameter for planar transducers. Double-sided is by no means an indicator that it’s better than single-sided designs. You can have good and bad instances of either type.

Now, getting to the stealth magnets… I’m told that conceptually this is intended to do similar things to what Audeze’s fazors do - and HiFiMAN have implemented this in some of their ultra high end headphones as well. But in practice, for these two headphones specifically, there doesn’t seem to be any meaningful difference. So while the drivers are different, I do not hear any difference between the two. Neither for tuning/frequency response, nor for subjective performance.

So I think the interesting thing here is that given the other parameters that exist with these two headphones, the stealth magnet implementation probably isn’t necessary. Now to be clear, I’m not saying this concept doesn’t make a difference, and maybe it makes an audible difference for their other headphones that have different parameters, but in the case of these two specifically, it’s a wash.

Here are some of the additional results that tipped me off that the drivers were in fact different.

HE-X4 THD (@100dB):

HE400se THD (@100dB):

Air gap differences (HE-X4 = Blue Dotted, HE400se = Brown)

It’s all similar and very… familiar, but different enough that it caused some head scratching. In both cases for THD I don’t think any of that stuff would be audible. It was taken at 100dB after all, and nobody is listening that loud (ideally). This is mainly just to see how it behaves when cranked up to potentially find any differences. And with the air gap stuff, it’s around the same spot, but there does seem to be some difference in overall level there.

Anyway, the conclusion here is that they’re both decent for the price, and the same EQ I used for the HE400se can be applied to the HE-X4:


Now if anyone is wondering how the HE-X4 and HE400se perform for their ‘technical qualities’, they’re generally solid for the price. They don’t suffer from too much haziness or graininess, nor the somewhat smeared effect of many other entry level planars. But at the same time, they are a little bit on the ‘sluggish’ side of things for the attack and initial leading edge transients. Soundstage is decent, definitely better than the Sennheiser HD6XX, but maybe not as evenly distributed as on the Sennheiser HD560s.

Overall, these both sound pretty good for the price. They’re both a bit lean in the sub-bass, and they both have the typical 2khz dip that HiFiMAN headphones often have. But on the plus side, the treble presentation is decently smooth.

I’ll summarize it like this:

  • Comfort - HE400se > HE-X4
  • Weight - HE400se > HE-X4
  • Aesthetics - HE-X4 > HE400se
  • Cable - HE-X4 >>>> HE400se
  • Sound Quality - HE400se = HE-X4

Which one is better? Well if it’s me I’d go for the HE400se due to the better headband and it’s about 30g lighter so it’s more comfortable. But at $129 the HE-X4 is the better value, especially because it comes with a cable that’s not at all terrible, which is something I can’t say about the HE400se.


Drop tells me that my HE-X4 should be here by the 17th. So, we will see just what it is like, and how well @Resolve 's EQ works.

Some relatively inexpensive fun.

Mark Gosdin

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It’s only two filters. I’m sure you could get more fine-grained if you wanted to. I just went the easy/lazy route here haha.


The distortion peak at 4.4k looks to be 10db greater on the HEX4. Isn’t that enough to potentially be audible?

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Doubtful. This is all amplified due to cranking it to 100dB.

Also, I think it’s important to realize that good THD does not equate to good microdynamics or ‘detail’. There are way too many counterexamples. At this level it’s not very important beyond showing that they’re different.


As I’ve aged I have come to have a greater appreciation of the easy/lazy route. :wink:

It’s been my experience that THD figures, like most specifications, need to be taken with a large piece of rock salt.

In any case I will know more about the HE-X4 in a few days and will report back.

Again, this is a fun hobby and I intend to enjoy it.

Mark Gosdin


Note to self : Just because you have a new phone with a fancy camera does not mean that you can take a good picture with it. Get the Pentax out if you want a good shot.

I’ve got the HE-X4 ( Henceforth X4 ) on my desk and attached to my daily headphone setup of FX-Audio DAC-X3 ( What is it with the “X + #” 's? ) and Tube-P1.

Initial listen, nicely balanced sound. Takes a bit more power, + 2 notches on the DAC-X3, than the DEVAs. More of an open feel than the DEVA, I can just hear that 60hz dip that @Resolve eq’d out. The 2000hz dip isn’t audible with this setup. Eventually will tinker with eq to see what good I can do.

Initial Impressions : So far I’ve listened to my usual test tunes, Mannheim Steamroller’s Fresh Aire 3 & 4 ( Organ & Orchestral ), Chicago III ( Accoustic & Electric Guitar ), Enya Watermark ( Vocals ).

As noted I can just detect the low end 60hz dip, otherwise plenty of Bass. Not quite as good as the DEVA, but close.

Mids are essentially identical, very pleasing to my ear.

The X4 matches the DEVA in high end,and conveys a more “Open” character.

Ergonomics : The X4 is smaller & lighter than the DEVA ( That extra $100 buys you some heft. ) but shows care was taken in it’s assembly. The Pads are comfortable once I got used to the sloped shape touching the area behind my ears. The cable is greatly improved over what the DEVA came with. Flexible and not microphonic in any way. The only issue I have with it ( There’s always something. ) is the length. At approx. 4 feet or 1.2 meters it is too short for use in my listening area. I’ve got 3.5mm extension cables but I wish I didn’t have to use one. Oh well.

Overall I’m quite happy with the HE-X4 and I believe it represents an excellent value at $129 from Drop.

Mark Gosdin


Picked up an X4 for fun, it’s tough to pass at it’s price. Still low hours on it, but so far so good. No quality issues yet. Sound is pretty good for the price. And it’s comfortable. It’s actually a pretty fun headphone overall, but does have some zing in the treble. Granted I’ve been listening mostly to ZMFs on a warm tube amp, so just about everything not that has some zing to it haha. I tried the X4 on my Kenzie Ovation low ohm tap, and it wasn’t bad. Very smooth and warm sounding. Very very smooth, with no treble glare at all. But it also sounded a bit flat overall. Bass lacked dynamic impact. And the overall presentation was just warm and uninspired. Since my Asgard 3 has been neglected, I brought that over for a try. Instant improvement! The Ovation just isn’t feeding the X4 the current it needs. The Asgard 3 has that to spare, and then some. The X4 came alive on the Asgard. Everything is faster, more impactful, and more dynamic. A much much more exciting listen. One issue though… that treble glare is rearing it’s shiny head. It’s not horrible by any means, but it is there, no denying it. Overall I’m enjoying the X4. It won’t stay for long i’m sure, it was an impulse buy. But for now i’m going to enjoy them and see how they grow on me. Iron Maiden is REALLY fun on them! The guitar is a tad bright, but man is it exciting! Live after Death - Phantom of the Opera is really blowing me away with it’s raw energy. Rambling over, Eric out!


Hey Andrew. Currently shopping for a pair of open backs. Can’t decide between the HE400i(non 2020 version), HE4XX, HE400se, or now the HEX4. HEX4 is the cheapest so I was wondering how the sound detail and quality compared to say the HE4XX?