HiFiMAN RE-400


New Head-Fier
It's wonderful!
Pros: Sound, ergonomic, quality
Cons: Nothing on this price!




HIFIMAN probably doesn’t have to prove to anyone that he knows about headphones like few people. Of course, provided that we like well-balanced and American tuning of the headphones. This time I will take a closer look at a very interesting and quite well-known in-ear model of this manufacturer, which is the HIFIMAN RE-400, currently costing about 79 USD. I cordially invite you to read it.

Unboxing and user experience.

First of all, we have an unusual situation here, because the headphones are packed in a hard plastic box, and additionally, accessories and a hard case are included separately, unfortunately without the manufacturer’s logo. The set includes ten paper filters for headphones that allow us to tune our headphones according to preferences. We also get a large set of tips, three sets with a double collar, one set of large tips with a double collar, three quite original white tips in size s, m, l. The headphones themselves are extremely small and do not have a detachable cable. Its lower part is secured with a braid, it also has an angled 3.5mm plug. On the distributor we have the inscription HIFIMAN and the name of the model. The rest of the headphones are not braided, but thanks to this we gain comfort of wearing. The domes are microscopically small and therefore fit perfectly in virtually any ear and provide excellent isolation and fit.


Moving on to what is equally important with comfort, i.e. the very sound of the headphones, I can safely say that the competition has something to be ashamed of.

The low tones are fast, definitely keeping up with bass or rock arrangements. The bass is perceptible and not overwhelming, which bodes well considering the current price of the headphones, which is USD 79. In this price range, we usually have strongly emphasized bass and its low quality, of course there are exceptions to this rule, but more on that in a moment. Low tones also do not flood the whole and give a pleasant rhythm to the whole. We can not only hear them, but also feel them. They are at a nice distance which further translates into a greater sense of depth and scene.

The mids are slightly spaced out on the V plan, have a dark but very balanced and natural character. Vocals are engaging and show details very well, for this price range it is very good. I like the balanced and very consistent character in the midrange. Vocals don’t sound flat but inviting to listen to, smooth but not lifeless which is a great result. In addition, the midrange shows details and layers very well for this price range.

They have been slightly dimmed, but they are promoted and consistent with the total tuning that HIFIMAN presented in the RE-400. The tuning shows the instruments great and not tiring, although they may be slightly dimmed compared to more expensive models, they are still safe and very nice for this price cap. Additionally, their purity and clarity are phenomenal. All this means that I definitely rate this model as extremely well-tuned.


HIFIMAN RE-400 ($79) VS iBasso IT00 ($79)

HIFIMAN RE-400 is a more V-tuned model, while iBasso in the IT00 model opted for U-shaped tuning. In the case of the IT00 we have stronger bass, a slightly closer and less linear midrange and more emphasis in the high frequencies. In addition, the RE-400 are much smaller, have smaller domes and do not have a detachable cable. However, at this price, this does not detract from their functionality.

HIFIMAN RE-400 ($79) VS AUNE E1($79)

The current price of AUNE E1 puts them close to the HE-400. The Aunes have much more top end and brighter tuning, but I personally prefer the RE-400’s natural and neutral presentation. Of course, this is a matter of completely individual preferences. Both pairs set the bar extremely high. Above their price ranges, which allows me to rate them on an equal level. If you like light tuning then choose aune e1, if darker tuning HIFIMAN RE-400 should be your favourite.

Soundstage and controls:
The sound stage focuses largely on the depth and quality of the transmitted information, the resolution is very good, but the width of the stage is average. This is not a defect, but a feature that this model is endowed with and you should just remember about it. The headphones are easy to control and do not require too much from us, which is their additional advantage. Although they really like the extra electricity and profit from it.

The HIFIMAN RE-400, priced at $79, is a great introduction to the winding and full of surprises world of audiophiles. Well-balanced and well-balanced V-shaped headphones with excellent bass, slightly recessed, but very natural and pleasant midrange, and a gentle and balanced treble. This allows me to place this model of headphones very high, despite the lack of a detachable cable, a stage not very developed on the sides, which they make up for with depth and the amount of details. If you’re looking for a big soundstage, reach for the aune e1 or it00, but if you give it a chance, the RE-400 will reward you with great musical presentation and excellent isolation and comfort of use. These are very good and noteworthy headphones that have my full recommendation.
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100+ Head-Fier
Hifiman RE400 Review - Neutral with a touch of warmth
Pros: High price performance ratio (20$ sale price)
Good technicalities
Smooth and balanced sound
Cons: For the price, really nothing much
Hifiman needs no introduction, it has already made itself well known in the audiophile community with various headphones ranging from the budget range all the way to their top of the line. Today I have with me the RE400 Waterline, which was released some time ago, i’m here to find out in today’s day and age, is it still relevant?
The packaging is very premium and not gonna discuss much about the packaging, you may refer to the pictures from Hifiman’s site.
Product Packaging Page
The only gripe I have with RE600 is the cable. It doesn’t look like it will break anytime, but it is easy to get tangled, the plus point of the cable is that it doesn’t have much microphonic noise. The IEM itself is also very light, you can go to sleep with it as well. The shell is made out of metal and the quality is on the higher side

Gears used for this review
  • Earmen Angel -> Earmen ST-Amp
  • iFi Go Blu
  • Hidizs S9 Pro Red Copper
  • Macbook Air M2 3.5 Out
  • RE400 with the Large white tips
My review is solely based on what I hear via my equipment and I never consider my reviews to be objective in any way rather a subjective approach. Do take into consideration that everyone’s ear anatomy is not the same, so the psychoacoustics perception might be different as well, but i believe it will not stray too far

Sound Impression
RE400 to my ears is neutral with a slight hint of warmth, to my ears, the low end although quantity is lacking, the note weight from the lows still carries sufficient weight/texture to it, paired with Earmen Angel, which is a reference sounding DAC/Amp, the dynamics are very impressive. The timbre sounds natural to my ears, nothing to complain about. Let’s take a look at the breakdown below:

  • Bass presentation is neutral, sub bass does roll off early
  • Not the star of the show, but the speed of it is very good, it handles high BPM song effortlessly
  • The bass has got a slight warmth to it, giving it a pleasant texture that doesn’t sound too thin
  • Mid bass has is punchy and doesn’t bleed into the mids
  • This IEM is definitely not for basshead nor it is suitable to listen to EDM
  • The mids are lush sounding to my ears, not recessed sounding
  • Vocal for both male and female are not recessed and has good texture to it, female vocal especially (Florence+Machine), it sounds sweet and has good texture with the right energy to it
  • Male vocal is not as forward as female’s, but it still retains good texture and note for male’s vocal
  • Treble is smooth and plenty of details in this range
  • However, there’s a slight graininess i noticed on this range
  • Doesn’t sound harsh nor anywhere near sibilant
  • It has got a good amount of air to not make RE400 dark sounding
  • Detail retrieval is good for the asking price, considering it cost only 20$, the technical performance is actually quite respectable
  • RE400 is fairly easy to drive, but as with most micro drivers, they perform better with more power
  • Pairing it with a slightly warm source, the iFi Go Blue, in my opinion is a very good pairing, the added warmth just thickens the overall note weight, a little bit more punch on the bass, with the xBass turned on, the whole experience is very positive
Comparison (RE600)
  • In terms of bass, both the RE600 and RE400 sounded very close, the difference is very minor during my A/B test
  • Construction wise, they are more or less the same in terms of weight, both of them are quite light, both have different cable, RE600 has better cable compared to RE400, which make sense because of the higher price
  • Mids on the RE600 is slightly more forward and more detailed compared to RE400, vocal performance on both is largely similar
  • Treble on the RE600 does have not have the slight graininess of RE400, detail retrieval is also better on the RE600
  • Soundstage is quite similar, imaging is where RE600 takes the lead, with much better imaging
  • In short, if you are tight on budget, the RE400 will do its job just fine, offering roughly 70% of RE600’s performance and fair asking price that will not break your bank
Final Thoughts
RE400 is the IEM that you don’t get the WOW effect when you first listen to them, similar to its bigger brother the RE600, it does grow on you as you spend more time with them.
Everything sounded natural and the performance of the mids is what really captivates me, having heard some other IEMs costing more than the RE400, the performance doesn’t come close except for the bass (more quantity). Released in 2013, is it still relevant today? Yes, I would say so. Recommended? Yes! If you want a no frill experience (No cable colling), prefer something neutral, look no further..

*RE400 is sent over by Hifiman for the purpose of this review. I thank them for the opportunity. At the time of writing, the RE400 is on a sale price of 20$ instead of the usual 79$, which is a steal in my opinion

Hifiman RE400 Product Page - Non Affiliated


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CK Moustache

100+ Head-Fier
Link to my review and measurement index thread where one can also find a full review overview, more information about myself as well as my general-ish audio and review manifesto: https://www.head-fi.org/threads/956208/

HiFiMan RE400i


Personal unit.


Plastic packaging appears cheap, but that’s okay.
Ear tip selection doesn’t seem to follow any real pattern – while many different pairs are provided, they sometimes differ considerably in length and properties; it would have been much better and more logical to include three different sizes of tips for each type of tip. Quality and texture is good, though.

Round storage case that is simply just an unbranded case without any logo. Protective, though.

Cable feels and looks cheap; cannot really be described as flexible. Strain relief not good and no chin-slider either. Quite microphonic.
The three-button remote control has a pleasant pressure point. Although the individual keys are not so easy to recognize as such haptically, it's still quite easy to distinguish the two volume keys from the centre key due to the size of the remote control. What I don't like so much is that the remote control is located on the left side. By the way, I also doubt whether the remote control is actually mfi-certified, because on my Apple iPod Nano 7G, the volume buttons remain without function after being pressed twice, no matter for how long, until I remove the in-ears and plug them into the jack socket of my iPod again (that even though I’ve got a genuine pair of RE400i without any defects), and on my Apple USB-C to Headphone Jack Adapter, a short press of the volume up button results in an irreversible maxing out of the volume.

Shells made of metal. Look very nice. Their build quality is good.

One dynamic driver per side.


Largest included black dual-flange silicone ear tips.


Fairly neutral leaning somewhat towards the warmer side.
Actually quite comparable to my InEar StageDiver SD-2 but with a brighter/less dark upper treble response.

Mild to moderate warmth in the root with the bass’ maximum quantity reaching around 5 dB in quantity above flat neutral at ca. 100 Hz in the upper bass. Flat extension into the sub-bass.

Ultimately a bit of warmth in the lower mids but not as much as my SD-2.
Flat central midrange with slightly reduced presence range but in the end still correct and neutral timbre.

Treble on the smooth and neutral/slightly darker side with a mild lift in the upper highs that ultimately leads to cymbals not always sounding sounding right but somewhat artificial/metallic. Never sharp or peaky.

Overall smooth, heading into a neutral direction and pleasant. Ultimately not as even as Etymotic’s in-ears but still some of the very best neutral-ish tuned dynamic driver in-ears regardless of price.

Perhaps the highs are brighter with shorter ear tips and/or a shallower insertion.

Frequency Response:


To my ears, there is no such elevation in the highs but just a mild lift.

ProPhile 8-Compensation


Decent but nothing that’s outstanding or special.

Somewhat on the softer/slower side without really becoming muddy. Would still be appropriate for the ~100$ original price and is clearly nothing to worry about when purchased at around half of that or below; good value.

- - - - - - - - - - - -

Compared to the Etymotic ER2SE:

Apart from the bass and root, the two are tuned quite comparably neutral, with the ER2SE however still taking the lead in the end due to their higher treble linearity and evenness (my RE400i are a bit more forward in the lower upper and upper highs, with comparatively more metallic, less realistic sounding cymbals compared to the Etymotic).
In the bass and root, the HiFiMan have got an elevation that is stronger than the ER2SEs’ by around 4 dB, which makes them sound bassier and warmer (therefore their tuning would be more comparable to the ER4XRs’).

The HiFiMans’ bass texture is softer compared to the Etymotic, and the ER2SE sound somewhat tighter in the lows, too. The Etys’ bass control is superior.
In terms of resolution, I see the ER2SE one or two leagues above my RE400i – they just sound cleaner and their minute detail resolution is higher, just like their speech intelligibility and note separation in fast and busy parts of the music.

The ER2SEs’ soundstage appears larger than that of my HiFiMan in direct comparison, especially in terms of spatial depth and three-dimensionality, while the spatial width is more or less comparable.
The imaging (instrument placement and separation) and especially the portrayal of “emptiness” around and between instruments is more precise on the ER2SE.


Smooth, neutral-ish sound that is heading somewhat into the warmer direction.
Rather “typical” dynamic driver technical performance but not muddy yet.
Cable could be better, just like the ear tip selection.


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New Head-Fier
A close to ideal IEM
Pros: - Absolutely distortion free no matter the volume
- Stellar imaging
- Smooth frequency response
- Very easy to EQ thanks to the many measurments available online
- Small and confortable
- Simple yet elegant designe
- Plenty accessories
- Can be found cheap nowdays
Cons: - Tuning out of the box is.. debatable
- The cable is not the most-well behaved
- Need to be inserted faily deep into the ear canal to achieve high frequencies linearity

I got those IEMs for 35€ at my local store. I have no interest in making good advertising for the brand. I only share my opinion hoping some find it helpful. I also aim at supporting/disputing existing measurments and consensus with subjective impressions.

What I'm lookink for: I believe EQ is the cheapest, quickest and more accurate way of achieving excellent audio quality with IEMs. This is why the ideal IEM should have virtually perfect electro-acoustic properties before anything else.

What I listen to: Wide variety of music, but mainly jazz, guitare oriented genres and modern mainstream pop & hip hop. Few classical tracks that I know well for reference purpose only.
I also use IEMs as a chirurgical tool when recording/producing, Occasionnaly for field recording (Etymotics are best for that).

Sources: 192 kbs ogg/ 320 kbs mp3 made from CD quality flac files or CDs on Rockboxed FIIO M3K/ Thinkpad x230 under Debian using Pulseaudio Parametric Equalizer and MPV.


It's surely not the most well built IEMs in it's pricrange. No flashy designe here... Just super discreet and simple. I like that. The lack of mmcx interface is a drawback though, and I don't really like the cable which lacks flexibility and sometimes gets on me nerves.

Tips: A lot of different types of silicon sleeves ar provided which is very nice. The small ones with waxguard gave me the best and most confortable fit. They allow deep insertion which is beneficial in this case. Sound isolistion was sufficient in most everydaylife cases, but pretty far from what an etymotic offers.

Sound: I see no drawbacks technically speeking. Well extended distortion free behavior is clearly shown. It feels almost unreal when turning the volume up. That is a sensation very specific to IEMs. The driver is extremely well damped, it feels precise and capable in very satisfiying way. Listening carefully really gives credit to innerfidelity and Rin Choi's Measurments. Just perfect.
Now tonally, it's quite off. The tuning makes it sound bloated, it severly lacks clarity. It's not unpleasant, but it cannot really be called neutral. It pretty much kills the chance to make it sound realistic and spacious. But you might like it, I have to admit I turn off EQ from time to time for a relaxing mellow ride.

When EQed: You'll have no trouble EQing to diffuse field or Harman target, or whatever sound profile you want. I personally use the Diffuse Field target a lot, it really manages to trick my brain, even slightly better than the Etymotic target (even if they are veeeeery close). These IEMs reacts per-fect-ly to whatever filter you apply to it: A perfect minimum phase system that can even handle pretty hardcore boost. Balanced armature based monitors or things like the Etymotic MK5 which uses an helmotz resonator as a tuning trick typically don't welcome EQ that warmly. In the end I found myself with something just as good as the ER2XR, even less distorted.

Conclusion: I just don't need any other IEM for my every day music enjoyment. If you're ready to experiment with EQ and elaborate a sound profile that matches your personal Head Related Transfere Fonction, it's just a perfect base to build upon. It's price point is very low now, and it can deliver pretty much everything the IEM world has to offer (perfect electro-acoustic behavior which translates into perfect "imaging" and cray amount of "details").
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Pros: Affordable
Cons: No bass
Treble peaks - sibliance
Response far from flat
Cheap cable
Bought them for $47 for my mobile believing the measurements used for full sized cans will have the same indication to real performance but found out the hard way the measurement don't apply the same way for IEM's - see this thread.

They aren't that much better than any Chinese $15 IEM. There are no free meals and to get quality looks like you'll have to be ready to part with $100 or more.
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100+ Head-Fier
Pros: Natural sounding
Really good midrange
Tiny and lightweight
Cons: Bass lacking
Cannot change cable
No controls on the cable
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Hifiman is one those brands that you cannot forget when it comes to high quality audio, the product range is complete and unique, with premium and reference material, from the budget oriented to the super luxury.

The main reason i like their products is because of the outstanding build quality and reliability; premium products are really expensive, but at the end of the day you get what you pay for.


My kind thanks to Hifiman for sending me the RE400 for testing purposes. My review is not biased in any way.


I really like the metal machinery there, precisely crafted, tiny and comfortable, during the first test i was really impressed how tiny and compact they are. The entire presentation of the earphones and accessories is nice and a really pleasing experience throughout: the casing, the foamy and velvety box inside, everything well presented and most importantly, well protected from the shipment; this is a really important feature because we have to imagine that the products travel all over the world before going into our hands. Design wise i would consider them minimalistic: the cable is not detachable, the first part of the cabling (the splitted part) is plastic only and the last part is covered with fabric, the two sections divided with the logo; L & R is printed behind the iem on the connection. On my version there is no mic nor input commands. I cannot stress enough how small they are, and in my opinion this is a good thing for a pair of all round easy fit and solid iem. I believe the connector has changed on a revision, as is now slightly different from previous model revisions, and probably more sturdy and ruggedized now. Everything comes within just 14 grams of weight, in line with other qualitatively equal models.
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· Sensitivity 102 dB

· Driver size 8.5 mm

· Frequency 15 Hz - 22 kHz

· Impedance 32 Ohm

· Weight 14 gr

Re-400 has a neodynium magnet and a titanium 8.5 mm driver; the loudspeaker has been designed and produced directly by HiFiMan to guarantee maximum performance of the medium frequencies. The technical specifications are in line with the earphones of the same price range; the sensitivity is 102 dB, the impedance is 32 ohms and the maximum power reaches 30 mW.

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Inside the package we can find:

· Hifiman Re400 In-Ear Monitor

· 7 pairs of Silicone Tips

· 1 carry pouch

· 10 Replacements for the nozzles filters

· 1 Clip

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Two main things to consider that i really like: the pouch included is a plus, and for the tips there’s a pretty good selection of them, wether you fit bi flange, small or big tips. There are no foam tips included unfortunately, and i do not understand why the tips are presented in 2 different positions in the packaging, as if the bigger ones are a later addition to the overall packaging: some are on the front in the casing, some are inside the pouch. One thing to consider is that the 3.5mm cable is not balanced, and cannot be detached from the units, however, there’s a moderately long strain relief (compared to the tiny bodies). The included nozzles filters are a nice addition, in particluar for people with a lot of ear waxing; when they become impossibile to clean and/or ruined, you can simply change them withut worrying too much.

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Overall the RE400 is a neutral sounding iem, the bass is a bit recessed and needs a some burn-in to shine in my opinion. I had to put the bigger tips to seal them better into my ear canals. The presentation is spacious and well-rounded. The soundstage is fairly large, and the earphones have a fairly open, airy, and uncongested sound.


The presentation of the RE400 is pleasant, wide and with a good overall sense of space and distance. There is less depth and height to the stage than with other multidriver iems, but the presentation is really good for this price point. Instrument separation is decent and overall very enjoyable. What i have found is a natural and pleasant presentation with great density that shines with an high level of clarity, especially with bright instruments and some particular tracks like the instruments found on the Chesky heaphone test disk.
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I have found the bass lackluster, even if i am not a basshead myself. With a bit of burn in it gets better, and i think that playing around with the correct tips helps a lot also. Definitely not a basshead iem, but i am able to live with it. The bass is there when you need it, but is definitely not so powerful. For a straight basshead i would consider something different, even if, to my taste, this can be enough and i was satisfied with the results after the burn-in process and the discover of the correct tip for my ear canals. Bass speed, on the other hand, is tight and precise, quick to play, and doesn’t linger too long; in my opinion this is really important. Definitely not a bass oriented iem, and again, if you are a basshead just choose something else.


Midrange is the best part of this iem in my opinion: it is very upfront and it blends very well with treble while retaining its space without going out of boundaries. The low-mids are well separated, and do not disturb some other frequencies; mids are really bright and some kind of vocals are better than the others: say for example forward female vocals are amazing: the overall result is a very open sound; obviously you miss some detail, some transparency, but at this price point, the midrange are really amazing, something that you are usually able to listen if you have an higher budget, on other brands.


I like the treble because it’s sparkling and vivid, but not fatiguing. You lose a little bit of detail in the treble, but nothing to be worried too much. The extension is fair; overall to my ears the treble sounds good; it feels more natural and it has a good separation from the other frequencies, if you think that this is a single driver iem, the result is pretty good for the price range. I like the fact, again, that you can listen to them for hours without fatiguing your ears, i think that this has to do with the natural sounding, even if the treble are really sharp. In my opinion the treble is not affected too much from the break-in process, not quite as much as the bass to my ears; they are consistent out of the box and after 50h break-in period.

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Overall sound impression:

Natural is the correct word for the RE400. The iem plays the music as it should be, without over emphasizing one thing or the other. The Midrange section is for sure the best one. Bass, on the other hand, is a bit lacking and you need some break-into get some and some good isolation, especially the sub-bass region, very recessed out of the box.

Final Impressions:

Well presented, natural and consistent: a nice tiny package that is good for the price and everyday listening without worrying too much about special sources. Buy them if you like vocals and midrange oriented tracks, do not buy them if you are a strong basshead and you want a lot of boom out of the box. Nothing special in the accessories, but the flange selection is nice, something they added later i guess, with the carrying pouch, that is a generic one and not personalized in any way with the name of the company or logos. I really like to listen to ambient tracks on those, especially filled with female vocals.

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PC + Fiio E07K @ Foobar 2000 FLACs

Rockboxed Sandisk Sansa clip+

LG G7 thinq with quad dac



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Thank you for the thorough review. I don’t find the RE-400 lacking in bass. The RE-400, thankfully, does not have that annoying bass “slam” or artificial bass boost like so many other IEMs. Though the RE-400 is quite competent, I find the ($99) RE-600 to be much more refined alternative.


100+ Head-Fier
Pros: Intimate and Emotional Vocal Presentation,
Balanced Sound Signature,
Fatigue Free Presentation,
Very Lightweight and Comfortable,
Lots of Ear Tips
Cons: Sparkle,
Treble Extension,
Maybe too Neutral for Some
Hifiman RE400 Waterline Review

Liquid and Relaxing like Water

About Hifiman:

Hifiman was founded by Dr. Fang in New York - USA and is one of the most well-known personal audio companies in the audiophile word.

Hifiman has a wide variety of Hi-Fi, Reference and Premium class products like Portable Audio Players, Planar Magnetic Headphones, Desktop Amplifiers and Earphones/In-Ear Monitors like the Hifiman RE400, which I will now review for you.



I would like to thank Hifiman for providing me this sample for review purposes. I am not affiliated with Hifiman and/or any third person beyond this review and all these words reflect my true, unaltered opinions about the product.


The Hifiman RE400 is available for 49,00 USD.

Package and Accessories:

The Hifiman RE400 In-Ear Monitor comes in a small rectangular box, which has a semitransparent plastic housing.

The box includes the following contents;

  • 1 pcs x Hifiman Re400 In-Ear Monitor
  • 7 pairs x Silicone Tips
  • 10 pcs x Nozzle Filters
  • 1 pcs x Shirt Clip
  • 1 pcs x Carry Pouch


The RE400 comes with a wide variety of silicone tips and some of them have a very unique shape like the bi-flange tips on the pictures bellow.


The carry pouch came separately, because the box is too small to carry all accessories. I think that Hifiman has added this carry pouch after some customer feedbacks.

The box includes also 10 pcs of Filters, which should help to protect the earphone’s inner components from dust and earwax.


Technical Specifications:

  • Driver Type : Single Dynamic Driver
  • Freq. range : 15 ~ 21000hz
  • Sensitivity : 102db
  • Impendence : 32ohm
  • Cable length : 1.33m
  • Plug : 3.5mm 3 Pole Unbalanced (TRS)

Design, Fit and Build Quality:

The Hifiman RE400 In-Ear Monitor has a pretty small and comfortable housing, which has a minimalistic design. The monitor housing is in silver color and is made of CNC machined metal that looks robust in my hands.


There is a small vent on the housing that is necessary to balance the pressure inside the housing.

On the front of the monitor is the sound nozzle that has a dust/earwax filter on the top, which can be replaced.


The cable of the RE400 is fixed to the monitor and is protected by relative long plastic strain reliefs where you can find also the left and right markings.


The cable of the RE400 is relative thin but and has a fabric coating which has pretty low microphonic effect. This fabric isolation goes up to the y splitter and the rest of the cable up to the strain relief is made of regular TPU material.


The cable has a plastic Y splitter, which sport the Hifiman branding and there is also a small metal chin slider in silver color same as the housing.


The Hifiman RE400 has a 3.5mm unbalanced 3 pole headphone jack with a 90 degree angled profile which is protected by a plastic housing.


The RE400 is very ergonomic due to the small and lightweight housing, which makes it ideal for long listening periods and to wear even while sleeping. The noise isolation is pretty good for an In-Ear Monitor with such a small design and has blocked much of the noise in relative noise environments like bus, train etc.


Equipment’s used for this review:

IEM’s : Hifiman RE400, Shozy Hibiky, Meze 12 Classics
DAP&DAC’s : Cayin N5II, Fiio M7, Chord Mojo, Xduoo XD10, Audirect Beam


Albums & tracks used for this review:

  • First Aid Kit - My Silver Lining (Spotify)
  • London Grammar – Interlud (Live) (Flac 24bit/44kHz)
  • Laura Pergolizzi – Lost On You “Live at Harvard and Stone” (Tidal Hi-Fi)
  • Minor Empire – BulbulumAltinKafeste (Spotify)
  • Adam Taylor – Colour to the Moon (Flac 16bit/44kHz)
  • Casey Abrams – Robot Lover (Tidal Hi-Fi)
  • Vivaldi – Le QuarttroStagioni “The Four Season” (Tidal Hi-Fi)
  • Steve Srauss – Mr. Bones (Flac 16bit/44kHz)
  • Otto Liebert& Luna Negra – The River (DSF) – Binaural Recording
  • Future Heroes – Another World (Tidal Hi-fi)
  • Lorde – Team (Flac 24bit/48kHz)
  • Tom Player – Resonace Theory “Album” (Tidal Hi-Fi)
  • Liquid Tension Experiment 2 – Acid Rain (Spotify)
  • Opeth – Damnation (Tidal Hi-Fi)
  • Metallica – Sad but True (Flac 24bit/96kHz)

The Sound:

This review is written after a burn-in process of approx. 70 hours and I have used the stock bi-flange silicone ear tips.


Sound Signature:

The Hifiman RE400 is an In-Ear monitor with a relative balanced, slightly mid-centric sound signature. The overall tonality of this IEM is slightly on the warmer side of neutral and is ideal for long listening periods due the smooth and relaxing presentation.


The bass of the Hifiman RE400 sounds pretty clean, controlled and very linear from the sub-bass up to the lower midrange and is nor bass-light neither bass-heavy in its presentation.

When it comes to the sub-bass region of the RE400, it shows moderate depth and rumble with average extension, which makes it not so suitable for genres like Trance and Edm music, but is good enough for jazz and acoustic music.

The midbass of the RE400 are tight, not very boomy and have the right quantity to add some warmness to the sound and to avoid a dull presentation. The bass speed is above average and has pretty good control for an IEM in this price category.


The midrange of the RE400 is where it really shines. It sounds smooth, forgiving and pretty detailed, especially at this price range. The positioning of the midrange is what it differs from other In-Ear Monitors in the same price class, because it sounds neither too forward nor recessed.

The overall presentation in the midrange is missing some transparency and is slightly veiled, which doesn’t sound unpleasant; on the contrary it gives the RE400 a special character. Both male and female vocals sounding quite emotional and pleasurable, especially female vocals have a more realistic presentation due to the brightness and sparkle, which comes from the upper midrange around 2-3 kHz. Male vocals are missing a slightly fullness and depth, due to the midbass / lower midrange tuning.

The upper midrange of the Hifiman RE400 sounds pretty controlled with a fairly acceptable level of sibilance and harshness. The song "My Silver Lining" of the group "First Aid Kid" is one of my new reference tracks to measure the stress in the upper middle range, which can be caused by female vocals, where the RE400 has done a great job.

The Hifiman RE400 sounds more realistic and successful with instruments such as guitars, drums and contrabass those have a relatively thicker tonality, than instruments like violins, flutes, etc. that are showing a thinner character.



The treble range of the Hifiman RE400 is very linear and balanced like the rest of the spectrum. There is a slightly boost in the 6 kHz range that is adding some clarity and definition to the overall presentation and is avoiding hollowness.

Some instruments like Hi Hats are slightly recessed, which makes it a bit too difficult to hear, while crash cymbals have a moderate extension. The Hi Hat cymbals are quite clear to hear in genres like Jazz, but harder to define in faster tracks like metal music.

The overall detail level of the treble range is pretty good for this price tag and extension is on a moderate level which is acceptable for an entry level In-Ear Monitor. The treble tuning is very ideal for those who are looking for an IEM that is fatigue free and ideal for long listening periods.


The soundstage of the Hifiman RE400 has moderate expansion, while the stage shows more wideness than depth. The stage has enough space to track the instruments in most types of music with low instrument quantities, but is not that suitable for songs with higher density, such as classical music.


Hifiman RE400 vs Shozy Hibiki

The Shozy Hibiki has more bass quantity than those of the Hifiman RE400 that shows a more linear bass response. The RE400 has less sub-bass rumble and depth than Hibiki with faster decay and less extension, while the RE400 is slightly faster and has better control.

The midrange presentation of the Shozy Hibiki shows a more V shaped sound signature with a more recessed midrange. The midrange of the Hifiman RE400 is more forward and intimate than those of the Shozy Hibiki. The midrange of the Hibiki has also a brighter tonality with more presence that is adding additional sparkle to the timber of the Hibiki. This relative high peak around the 3-4 kHz makes the Shozy IEM prone to sibilance and can cause to ear fatigue. This was very noticeable in the song "My Silver Lining" of the group "First Aid Kid" where the Hifiman RE400 sounded much smoother and controlled than the Hibiki.

The treble range of the Shozy Hibiki is brighter and more pronounced in the 8 kHz region which is increasing airiness and sparkle, while the Re400 has a more natural and linear treble presentation, which makes it to the more ideal IEM who prefer less brightness and more relaxing presentation.

When it comes to the soundstage performance, the Hibiki shows more depth, while the difference for wideness is less noticeable, maybe slightly better with the Hibiki.


Hifiman RE400 vs Meze Classics 12:

The Meze Classics 12 has a more V shaped sound signature than those of the Hifiman RE400 with emphasizes to the lower and upper frequency regions. The sub-bass quantity and depth of this two IEM’s is nearly identical, while the RE400 has slightly better extension.

The bass and midbass region of the Meze 12 Classics sounds fuller and has more impact than those of the RE400 with pretty equal speed and control.

The midrange of the Meze 12 classics sounds more recessed than those of the RE400, which has a more intimate and emotional presentation for vocals. The boost in the upper midrange region around 2-3 kHz makes the RE400 more successful with female vocals and is adding slightly more detail without to be sibilant ant harsh.

The treble range of the Meze 12 Classics has a noticeable boost around 4-6kHz with a peak at 5 kHz that is adding more brightness, air and crispiness compared to the RE400, which has a more linear tuning. The Meze 12 Classics has treble extensions, while the Hifiman RE400 has better control and offers a more fatigue free listening.

The soundstage performance of those two IEM’s shows not a night and day difference. The Hifiman RE400 and Meze 12 Classics are performing head to head in terms of soundstage wideness, while the Meze 12 Classics has better depth performance.



The Hifiman RE400 is very lightweight and comfortable to wear In-Ear Monitor with a smooth and relaxing presentation. The great vocal performance makes the RE400 to a real joy, especially with acoustic songs, while listeners who prefer more bass in their tracks will be less satisfied.

Pros and Cons:

  • + Intimate and Emotional Vocal Presentation
  • + Balanced Sound Signature
  • + Fatigue Free Presentation
  • + Very Lightweight and Comfortable
  • + Lots of Ear Tips

  • - Sparkle
  • - Treble Extension
  • - Maybe too Neutral for Some
A good iem for the price, but with one of the worst cables ever made, at least to me :)
Nice review. Thanks. This seem like great option for Xiaomi Pro HD's upgrade


Member of the Trade: Audio Excellence
Pros: price. neutrality.
Cons: bass may be lacking for some


ALL REVIEW ARE DONE @ SOULSIKREVIEWS.COM and more insightful review can be found on our site.


If you are on a budget then you are in for some good luck because Hifiman re400 might be just for you. Hifiman claims this IEM to be the “waterline” IEM, which means, not only them but the industry should be doing THIS with 99 dollars. Bit of a big claim? But I must say, they deserve the big talk. The re400 is not only small and compact but brings you quality that you would see in much higher end IEMs.


The Hifiman re400 was sent me for a review by audioexcellence, a audiophile store in Canada. As usual, my reviews are not bias in any way.

ABOUT Hifiman

HiFiMAN Electronics is a designer and manufacturer of audio products including headphonesamplifiers, and portable audio players. Hifiman is known for its high-end audio products made under the brand Mee Audio. Its most popular products include the HE-400 which are full sized open back headphones and the RE-400 which is an IEM (In Ear Monitor). Both products are supposedly critically acclaimed for their sound quality


Divers: Titanium coated 8.5mm dynamic drivers

Frequency: 15 – 22 Khz

Sensitivity: 102 dB

Impedance: 32 Ohms

Cable length: 1.33m

Plug: 3.5mm



If you are in Canada, https://www.audioexcellence.ca/ is the place to go, not only for this product but for any hifi products, their price is competitive and ensures quality service. Their store is well worth a visit if you are located within the GTA.

Internationally, amazon is your best bet far as I know.



HOUSING: the housing is made of aluminum and is very small and compact.


Cable: the cable is fabricated cable up to point of the splitter and then it is

rubber/plastic material from then on. The slider is metal, which is very nice touch. It terminates in a 3.5mm gold plated right angled jack.


Accessories: A lot of tips for any fit, however I found the comply foams to be the best. A very nice hard carrying case that is practical in size and portability is included. There are also extra filters in case you damage the filters with earwax, which is a nice touch and shows that HIFIMAN wants you to keep the IEM for a longer time.


Overall, the build quality is exceptional for 99 dollars. From drivers to the accessories, it screams quality. Also, the isolation and fit was perfect for me. There is 2 ways to wear it. Straight in or over the ear (found the 2nd fit to eliminate any microphonic)


This IEM would be something I would recommend my university friends that are not audiophiles because of its cheap price point and what you get for it. With the comply foams, there was much more isolation, however even with the normal tips included with the re400s, the sound isolation was enough to be used in quiet places like the library and loud places like the gym.


GENERAL: These are neutral sounding IEMs. The bass is not as extended as modern bass heads might like it, and this might be a turn off for some people. However, the fact that you can hear the music you love, the way it was recorded, the way it was supposed to be heard for 99 dollars, is something to appreciate. If you are like me and listens to almost anything, these are perfect. You can hear these for hours and hours without any problem because there are no sibilant highs or no booming bass that might bother you in long listening sessions. Everything is clear and represented “the way they are supposed to be”

Sound Stage: the sound stage is very intimate, which may be a good thing for some and a turn off for others. Again, priced at 99 dollars, these are exceptional in sound stage and imaging.

Final Thoughts

Hifiman re400 really did amaze me with its price to performance ratio. I wish to see more budget iems like these in the future. I truly believe they deserve the title of “waterline.” 

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You may like the Ostry KC06A even more that are sub $100 which almost sound like the RE-600 and more mid forward if the RE-400 impress, they just more bass but not by a lot. I call the Ostry's HIFIMAN on steroids compared to my RE-600's. Give them a try. They won't disappoint you. I have both and love them equally.


100+ Head-Fier
Pros: Delicate and trully musical, timbres, fatigueless
Cons: Very slightly warm sounding, not as spacious as other's
I am only listening to acoustic music, So I had no issue with the amount of bass (only plugged to my FIIO X5II, Flac, APE, Highres and DSD files). Even though they are not as tight as on my Shure's Se425 they are well balanced with the rest of the spectrum.
Slightly on the warm side but perfectly balanced, not in the face , musical, smooth apart from a little peak on the high mids, they have an amazing respect for the timbres, which is for me the main point.
The relative lack of definition participate to how "liquid" the music is just like in concert. Everything is integrated in a delightfull way, not much sticks out.
On some tracks I was expecting a little bit more dynamics but I have never heard a pair of IEM's that accomodate so many different style of recordings. 
Bought second hand (perfect condition) for 40€, it's the bargain of the century.
Higly recommended for classical music lovers.


500+ Head-Fier
Pros: Smooth neutral sound, amazing soundstage, very detailed yet not fatiguing at all.
Cons: Supplied ear tips may not get a comfortable seal.
Where do I start? These honestly sound like the HD600/650 in IEM form. My previous go to IEM was the Klipsch X10 ($100), followed by the Klipsch X20i ($539). What is amazing, is that the RE-400 sound smoother, are more realistic, have better treble extension, AND have better soundstage than the X20i. And these cost just $79! I am continually impressed by these the more I listen to them. They seem to work with every genre too. For classical, they bring out every instrument texture to make them sound realistic. For pop and EDM, they have decent impact and sub bass extension, but are not for bassheads. I would describe them as neutral, and very slightly warm. Some may say they don't have good sub bass, but I disagree. If you are used to Hifiman's planars like the HE-400i and HE-560, you will notice these have extremely similar bass presentation. Mids are fantastic, very realistic and right where they sound be. Maybe slightly elevated compared to most IEMs, but only very slightly. Treble is so smooth, no peaks at all. I must say, the tonal balance is smoother and more realistic than many over ear headphones such as the Beyer DT800 and T1, Hifiman HE-400i, and Shure SRH-940, and sound very similar to the Sennheiser HD600/650 in the mid and treble regions.
The only con I can think of is the supplied ear tips may not fit people with smaller ear canals like me. The smallest size is ok for me, but doesn't seal as well as foam tips, and the next size up is too big. So I ordered Comply foam tips (the TS-400 size) and hopefully those will get a better seal. However, even without the best seal, it doesn't seem to affect the sound that much, because they already sound fantastic. 
Considering these sound significantly more balanced and natural than what the Klipsch IEMs have to offer, at under the $100 price point, is a huge accomplishment in my book. You probably wont find a better sounding audiophile IEM under $100, or maybe even up to $300. I wouldn't be surprised if these match the performance of the king of dynamic IEMs, the Sennheiser IE800. Hifiman sure knew what they were doing with these, and I can't recommend them highly enough!
klipsch are crap in terms of price/performance ratio so no surprise there.
@seanwee yeah, they really are aren't they? I never realized just how outperformed they are until i tired the RE-400. Guess ill have to try other brands instead.


Pros: Good balanced sound, Solid build, Comfortable
Cons: No in-line controls
Source: Macbook 12 with Audioquest DragonFly v1.2
Comfort and Construction:
Overall the comfort level was good to me for an in-ear monitor. The key is to correctly size the inserts. Cord length is good for this type of ear monitor. Ended into a 1/4” plug with a 45 degree angl. For use on an iPhone or iPod, this may be a slight distraction. The cord is sturdy. Seemed to have good thickness without being too thick. There are no controls on the cord. This could be a deal-breaker for some.
Overall, the RE-400 has a good sound. The highs are crisp and detailed. The mids are solid. It does lack base, but most in-ear monitors will be the same. Isolation is good for an in-ear monitor. No active noise cancellation, but with a good fit using the correct inserts, the isolation is satisfactory. I was impressed with the clarity of these. Good sound separation.
Easy to recommend if you are looking for a reasonably priced in-ear monitor. Good sound and comfort. Need to decide if the angled plug will detract or lack of in-line control forces another choice.
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Headphoneus Supremus
Pros: flat frequency response, excellent timbre, quick, very clean decay, inexpensive, comfortable, discrete fit, impact, not BA, responds well to EQ
Cons: benefits from EQ, not much high treble extension
A bit of background:
I have never really been that into portable gear.  I have already sunk a lot of money into my home setup, it is more comfortable to use than in ears, more conducive to critical listening, and generally I like to be aware of my surroundings when walking around in public.  I am however well past the point of diminishing returns with my home setup, and occasionally its nice to tune out from the unpleasantness of public transport, plane travel etc. and still have an acceptably engaging and truthful sound quality from portable equipment.
In any case I am used to over ear desktop sound.  Relative to my desktop gear in the price range I am looking at is compromised in one way or another.  More often than not with multi balanced armature in ear monitors there are certain colourations due to the BA drivers themselves, crossovers, peaks and dips in frequency response.  More often than not the BA headphones I have tried exhibit an airy sound quality that sounds nice and detailed, have excellent separation and detail.  More often than not though you know you are listening to a multi BA earphone.  The JH Layla was an exception, showing little of the usual BA colourations (not airy or soft), having excellent dynamic impact and incredible imaging.  Eventually though I tired from the lack of micro detail resolution and poor fit, and incredible local cost (our currency in Australia has dropped in value).  I sold them and went back to my Westone 4's.
Anyway the trend with multi BA earphones seems to be stacking more and more drivers to develop a more forceful detail presentation and dynamic impact, and get away from that sort of vapid airy BA sound.  This however is very costly and more often than not still results in peaks and dips and phase irregularities and other colourations to the sound.  Coupled with the weakening Australian dollar, chasing high sound quality using multi BA based earphones is getting expensive.
Recently my Westone 4's died, so I went on a search for replacements.  I tried a lot of the new multi BA options.  They are making progress in sound however IMO are still quite compromised in sound quality versus full sized earphones.  I also tried some of the new extremely expensive dynamic in ears (I won't mention names).  They had some nice qualities but again have substantial coloration to the sound mostly due to uneven frequency response and ringing distortions.  I am always happy to see new research and development in dynamic in ears but I don't fancy spending big money on (still) flawed products.
Now to my review:
I think my demo of the HifiMan RE-400 was one of the fastest purchasing decisions I have made.  Compared to the other in ears I was testing, they just sounded so "right" with a flat midrange and such natural timbres!  I have had other similarly quick demos but those mostly involve me ripping headphones off my head because of how badly coloured they are, but that is another story.  RE-400's were clearly the most faithful earphones I had heard that day regardless of price (I had listened some earphones costing 20x the price of RE-400!)
Anyway I think it is customary to break reviews down into sections, maybe BASS, MIDS, TREBLE etc. so I might do the same:
BASS:  Flat.  Not elevated or rolled.  Just flat down to 20 Hz like a planar.  Tight.  Not boomy.  Detailed.  Acoustic.  Fast.  A little shy when not driven with enough power.  Excellent.
MIDS:  No peaks or dips.  Clear.  Perfect timbre.  Fast and clean.  Resolving - this is not the same kind of (overly) airy sense of resolution you get with BA earphones, and subjectively there is not as much finer microdetail as some of the multi BA solutions, but the overall faithfulness of timbre is higher and resolution is hardly lacking*.  *Actually I think part of the subjective impression of resolution might be down to the frequency balance which I will discuss that later.
TREBLE:  Good timbre, moderately good extension.  I can still make out all the cymbals and acoustic instruments all sound remarkably lifelike.  There is some lack of air due to rolloff in the high treble.  Mid treble also needs some boosting with EQ.  I added +6dB centered at 6kHz and +10dB centered at 16kHz, however you may find different adjustments more to your taste.
I use these earphones with my Sony ZX2 DAP, which from experience may be slightly lacking the power to make the bass wake up but, interestingly the RE-400 are not holding back this high end DAP. The RE-400 will improve with better gear such as Chord's Mojo, or even some other higher powered DAPs.  The RE-400s are incredibly transparent and revealing.  Colourations in source components or amplifiers are laid bare.  They are not harsh (though there is some very slight sibilance splash).  Yes it makes sense to use this (USD) $100 earphone with high end portable gear like Chord Mojo, Sony ZX2, Astell & Kern AK240 etc.
I mostly listen to classical and jazz, however I still listen to some heavy metal.  With classical and jazz the technical prowess of these earphones is hard to beat at any price.  For heavy metal, the technical ability and truthfulness is usually also good, however poorly recorded material will sound however it sounds.  I can just back off the treble EQ to compensate if the recording is too harsh for high volume listening.  When playing acoustic music you want to be able to appreciate the full performance in all it's nuance and dynamics.  Timbres are very convincing.
Anyway I could continue to waffle about the technical ability of this earphone, however at the end of the day it will be up to the listener and his gear, music and tastes to determine if they like this earphone or not.  I almost overlooked these earphones, firstly because of the price (I think many others do as well), but secondly because I was not aware of just how good they are regardless of lack of hype.  I am sure that the few listeners with good ears who have discovered these gems are happy that their performance is not widely hyped.  It's a small miracle that this level of sound quality can be found for so little money, especially considering the general trend in the market towards more costly designs.  I recommend for everyone to try these earphones, especially audiophiles who value neutral, transparent, and low distortion sound.  Do NOT make the mistake to overlook these earphones because of the low price.
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100+ Head-Fier
Pros: Beautiful midrange, tonality, no sibilance, smooth, mellow treble
Cons: Severely lacking in bass response, build quality, narrow soundstage, lack clarity
Unfortunately, I find these to be the most overrated iems going on the market at present. Anybody who claims that these have sufficient bass response are just deluding themselves, or others. They are extremely bass shy, to the point where it just ruins the music. I also own the Trinity Deltas, Vsonics vsd3s, and senns cx-300ii; and the Hd-600s and Fidelio x1 for full sized cans. Even next to the hd-600 which is hardly 'bassy' is not lacking in this department, while the re-400s are just deflated there. Such a shame.

The midrange is lush and smooth, and the treble is just right. The soundstage is very narrow, however, and the presentation lacks clarity and transparency. Also, the build quality is truly terrible: the wire  from the Y split to the driver casing is very thin and the actual connection to the case is weak (it separated barely 6 months into usage). The tip assortment is fine, with the Comply Foam tips giving it a bit of extra bass hump it sorely needs. However, they make the presentation even narrower and more congested than it already is. Sillicon tips uniformly give the same bassless response.

These are horrendously overrated.
I loved the sound, bought two pairs and both died the same way.  One side failed.  Considering how many earphones I've bought (both less and more expensive than the RE-400s) that have had no problems I've resolved to avoid HiFiMan from now on.  They're great at tuning but their build quality and quality control is sub-par.
I think these builds may start to be a thing of the past? How HiFiMan can get away with this level of build quality is beyond me. This style of quality could be tolerated 5 years ago. Now you have $16 Piston 3 headphones which are built 10x better. It's not just that the HiFiMans always failed right at the mini-plug, but if not there, a driver would always fail on one side in time. These issues are not a question of if, but when. It's a quality that should put a product on a flag list of some type. Audio-fools, I mean audiophiles are a strangely forgiving group at times like this.
These made me single-handedly doubt the entire audiophile verdict. These are simply mediocre, the build is indeed atrocious. And though the tonality is quite natural, you simply can't justify the lack of bass without ignoring the visceral quality of the music. 


New Head-Fier
Pros: Absolutely heavenly sound. Unbeatable at this price point
Cons: Build quality on my unit is a joke. Cable is falling apart 2 days in.
***This is a tl;dr: review. please refer to other reviews for a more in-depth analysis on their amazing sound.***

For $100, you simply won't be getting anything better sound-wise than these cans, and a lot of happy owners will back me on this one. The mids are heavenly, the treble is smooth yet detailed, and the bass is tight and accurate. However, don't buy them just yet. The build quality is not up to scratch. In fact, when I asked the saleslady for these cans, she immediately suggested that I get it recabled from the get go. How I wish I took her advice. Barely 48 hours in and the cable on the right earpiece is fraying, just below the strain relief. The copper has gotten exposed, and while photos might not do them justice, and while $100 is relatively cheap in audiophilia, it is ridiculous that they are showing signs of tear 2 days in.Absolute let-down. Granted, YMMV, and I might have gotten a faulty unit because some owners have owned them for years and theirs are still apparently alive; however, if you plan to use them on the go or while exercising, look somewhere else, or get them recabled.

I will update this review if my unit breaks. It's a shame really, I dig the sound so much. If they do break, I'll definitely be getting them recabled at cost. I dig the sound that much. Photo of the fraying cable below.

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They sound good for $100, but they are easily outclassed by the Titan 1. I actually didn't have those build quality issues with mine though, maybe you can send them in for warranty? 
@AvidlyEclectic : I haven't had issues with my pair (over 1.5 years now) save a slight nick at the Y split. If you are a careful user, RMA them, and if they last for more than 7-8 months,you've probably received a good pair. BTW, where will you be doing the re-cabling, if needed?
Hi @lin0003. Love your reviews.
I feel the RE400 and Titan 1 differ in their base signature(Mid forward vs Slight V), which makes it difficult for me to place one over the other (personal sig preferences aside)
@lin0003 I wish I could, but I'm from the Philippines and sending it to hifiman will easily cost as much as the iem itself. I'll try my luck at the store I bought them from though.

@getclikinagas just the local audiophile store I bought it from, Egghead. I think the owner has a head-fi account.


New Head-Fier
Pros: Excellent mids, decent price
Cons: bad sibilance, comically weak bass, unattractive, poor build quality, not very comfortable, microphonics
I bought these in early May based on nearly unanimous recommendation from people on a bunch of websites, and I must say they don't live up to their reputation. Some of the common things people pointed out were that they are excellent for the price, they have great mids, and they have bad build quality, the bass could be better, and that they are great for all genres. Most of these points definitely stand up, I don't think I have ever heard better mids in my life, they are fairly cheap, but to me they have nothing else going for them. The bass isn't just leaving more to desired, it is so bad it makes some genres hard to listen to, it is almost comically weak, more like a tickle than a punch. They aren't especially neutral, they are just very mid heavy. I guess it sounds neutral at first glance, but the lows are extremely recessed, and the highs aren't very sparkly, they also have bad sibilance in a lot of cases. It is basically the opposite of the classic "V-shaped" sound signature, whereas normally mids are recessed and there is too much emphasis on lows and high, these have way too much emphasis on mids and bad lows and highs. They also definitely don't work for all genres. When listening to classical instrument seperation suffers, soundstage seriously suffers, bass suffers, highs suffer, and volume suffer. For metal the vocals are amazing but a lot of the rythm is lost in the weak bass, funk is amazingly smooth and probably the best genre for these, for techno in general they are terrible due to the bass problems, although as usual vocals stand out and are excellent. 
In terms of physical qualities they aren't great either. They look quite cheap, which is the downside of their otherwise nice minimalistic style, the 3.5mm jack is very obviously low quality, as someone who fixes headphones on a regular basis that stand out like a sore thumb, the cord definitely also feels a bit flimsy and I don't expect it to last long. If you don't wrap your earphones around the back of your ear these suffer from constant annoying microphonics leaving you with no obvious choice except to wrap the, but they also have a tendency for the wire to constantly fall off my ears, which can get very frustrating at times. The sound isolation is mediocre, nothing really to complain about but also not worthy of praise, I often have to bring the volume up a lot compared to where I normally do with IEMs. The choice of included tips is strange to me, there is a bunch of flanged ones that scratch and irritate the inside of my ears, there is ones that are way too small, ones that are way too large, and only one set that is similar to what is normally included with all IEMs which is medium sized rubber tips, but it's still not exactly the same it's like a half flange, the tip is two different sizes but it isn't separated, 
In conclusion, I definitely do not recommend these earphones. I have had 40 dollar Sony earphones perform twice as well as these for less than half the price, and they lasted me almost 2 years, where these apparently have a tendency to fail after only a few months. These are an exceptionally mediocre pair of earphones with a huge list of major downsides that are only redeemed at all by the excellent mid range performance.
Must say I agree. Anyone who says these are anything but very bass-shy they are deluding themselves, or others. The treble is also quite mellow, and not very well extended. The mids are great, but overall the sound profile is congested, dull, with a cavernous soundstage. The build is pretty bad as well. These are the most overrated earphones I have heard.
I agree with you, I marvelled at the detail i was hearing but in time it started hurting my ears how clinical these sound... very cold. The bass is heard but very very low. i also wear AKG K451s which are bass heavy and very warm, which i like but i was fed up wearing them in hot weather. Sadly when i go back to them it makes the 400s sound so much weaker and boring sounding. Cable noise is horrendous. I too got suckered in with the insanely high reviews
Sibilance on these ? You must be joking or having recieved a broken pair ! These highs are one of the smoothest ever heard on IEM's . Unatractive ? Are you talking about my mother ?... let's say discrete and let them desappear... Give them a decent source on a decent amp/dac and you might change your mind?
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Apex Eight

100+ Head-Fier
Hifiman RE-400: Eye/ear opening sound, poor build
The neutral, balanced sound of these earphones made me realize what good audio could sound like. They reveal and retrieve so much detail, which at first can come across as only thin and lifeless, but if you're like me, that's because you are used to hearing bloated, bassy equipment that is made to appeal to the masses.

The metal housings are nice, but that's about the only good thing about how they physically feel. Their build quality and durability are poor, the cable is lackluster, and the eartips feel cheap.

I believe I paid close to $100 for these back in 2014/2015. They're currently on sale for $20 through Amazon and Hifiman. At $20, they're a no-brainer for sound, even in 2021, imo. But the fact that they will eventually break much sooner than earphones of this caliber should, gives me hesitation. I would gladly pay $100-$150 for a MMCX/2-pin version from the factory.

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hi all! how is this compared to gr07's mids and treble?
Four years later and still hasn't finished the review yet, lol.
Apex Eight
@NeonHD, totally forgot about this lol. Here's to keeping promises in 2021.


New Head-Fier
Pros: Neutral, good to have, 45 degree plug
Cons: Neutral, could use a bit more bass, Microphonics
Build / Fit
They are much smaller than I expected. The aluminum casing is nothing too special, it looks very clean, and simple. The wires above the split are very thin with a feel like they could break easily if you use then regularly on the go. But, below the split is a very nice cloth cable that leads into a 45 degree plug. The fit seemed very loose, even with the comply tips.
Neutral with a very slight rise in a bass. For the price, even for the $99 MSRP, they are incredible. The detail and sound stage are as good or better than some full sized headphones I've listen to. IMO the bass could use just a bit more impact?, not too much though. The Highs were just great, non-fatiguing, but still held the detail very well. The mids are neutral, nothing sounded too out of place. Again, for the price you can not get better than this. There is a reason why HiFiMan calls them the waterline.
I guess this is something take into consideration? I thought is was very simple, clean, like the headphones that lay inside. There is a thick plastic sleeve that I thought was neat.
They are fantastic pair of IEMs to keep in your collection, I will be using them when I am too lazy to put on my SE-215s or is a rush. BTW, Microphonics are a thing. I love the RE-400s, but they feel like something was holding them back from being spectacular.

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in regards to the microphonics i agree entirely, thats why i use these exclusively over the ear (wrapped over my ear).
its quite bothersome. the build is another issue (its quite underbuilt for its price tag)
but the sound is just in another league. its simply clean, transparent without sounding cold or analytical. it walks a very fine line and does it effortlessly.


500+ Head-Fier
Pros: tactile balanced sound, good details for price, light and comfortable that looks good as well.
Cons: a little lacking in sub bass.
I have been using RE400 for over few months now. these are rather well known and well documented so I will only put stand out points that I think make it unique.


Light weight, made out of aluminium. Chord is fabric covered below y splitter. above that its plastic. no microphonics if i wear them from above my ears. Otherwise it can be bothersome. Jack is 45 degree. Overall looks solid and mine is working well without problems.

Comfort and isolation:

Comfort is above average. Isolation is great if I use comply tips, otherwise I think its above average. I do need to insert them a fir bit in my ears to get a good seal, more than other IEMs I have used.


Two words that best describe the sound is: Tactile and balanced.

Bass is present and slightly lifted thus gives instruments slightly more realistic feel. Bass is Fairly transparent and conveys what was played well enough. Its fairly tight, though I do find sub bass lacking a bit.

Mids are well balanced with bass. Its not a huge soundstage and mids sound rather intimate. Slightly lush, overall maintain neutrality.

Treble is extended and can be delicate or harsh depending on source, with fair amount of resolution. Again nothing alarming, its not a bright sound to my ears.

Amping: Rather strange in amping department (I guess its common with iems). Sounds best out of my PS Vita, a gaming console, compared to my phone or amp. Detail retrieval drops when used with either compared to my other full size hps, that sound best out of amp.

Value: Overall amazing. I has quiet a lot of hype surrounding it. I do think if you factor everything, comfort, accessories, sound, its very good $100 iem. Taken only in terms of sound, will it beat a $200 hp? I don't think so. But I do think its very competent hp for $100 and a great value.
it's a love and hate relationship my experience with RE400 :)
i do like them and use them for portable use. definitely thumbs up from me.


Headphoneus Supremus
Pros: smooth sound, good detail retrieval, forward midrange, tight bass, extended smooth highs, excellent imaging and separation, decent soundstage width
Cons: bass a bit soft in punch at times, initial build quality
HiFiMAN RE-400 Waterline - Ultimate Review w/ pictures
1)Equipment and cabling
HiFiMAN RE-400 Waterline
Type: Closed, tiny, in-ear, dynamic driver monitor
Frequency response: 15 - 22.000 Hz
Impedance: 32 Ω (may vary by up to 10%)
Efficiency: 102 dB
Weight: 16 g (with cable)

This was my first in-ear-monitor purchase. Also the very first IEM made by HiFiMAN. Their cheapest headphone yet, priced at 100 USD. How will these compare? They share the general HiFiMAN house sound and neutrality and offer good build quality as well. There is a dedicated RE-400 review below where all will be discussed and compared.
b)Amplifiers, Digital to Analog Converters, Preamplifiers and more
Fiio X1
The X1 is an amazing little unit. In fact, that is an understatement. It's been a very long time since last time I was this overwhelmingly impressed by a $100 unit. The UI is excellent. Very intuitive, rather snappy and easy to navigate. Honestly, I was not expecting an in-house developed UI to be this good, but it every bit is, and it also reads all the formats that I've tried without any hiccups, including associated CUE files. The DAC is absolutely stellar, using an impressive Texas-Instruments PCM5142 DAC chip. The amp section is also pretty good, utilizing an Intersil ISL28291 amplifier buffer. The 2.4" TFT display is plenty big and easy to read, providing all the necessary information even in direct sunlight. It is slightly washed but still plenty good for the price. Among other things the player offers a 7-band equalizer [from -6 to +6 each], gapless playback, sleep timer, usable buttons when screen's off or volume limiting. There's no date and time yet though, which I find a bit strange though not all that important.
The build quality is perhaps the most spectacular aspect - holding the unit in your hand boasts confidence and there's good heft to the unit. The X1 features a fully-aluminium body with very tactile buttons and quality that's hard to find on products costing much more. The Fiio also comes with a screen protector and a rubber protective case, along with a charging cable. The battery life is around 12 hours a run, for a 4 hour's full charge.
There's also the line-out function using the headphone jack, which offers the possibility to use just the player's DAC with a more beefy portable amp. Although I already found the X1's amplifier to perform favorably with reasonable headphones from IEMs to full-sized cans.
I am really struggling to find anything to criticize here... Did I mention it was a hundred bucks?! In a long time, I am left with only fuzzy and completely positive feelings, while using the unit feels just as enjoyable. I really don't understand how Fiio did this, but currently I consider the Fiio X1 a jack-of-all-trades and wouldn't hesitate recommending it to anyone looking for a lovely little DAP and as someone coming from the pretty good, very-happy-with and tried-and-proved Sansa Clip+, I think this is some very high praise.
There's more competition on the way, however 

+ build quality
+ performance
+ User Interface
+ price, price, price!
+ line-out function
- no time & date, slightly washed-out display
Overall 9.5/10
Fiio E11

A very versatile little amp.
Slightly warmer tonality with smooth highs. Decent instrument separation and soundstage. Ideal for most portable headphones. Fits your pocket nicely. The stock battery lasts about 8 hours.
Packs lots of power. For 60 bucks it is hard to beat. Fully aluminium casing (like all amps here). Has a bass boost switch as well as a low/high gain one. Fiio is getting very popular among audiophiles these days because it offers good quality throughout for the price. The E11 is no exception
+ Small
+ Decent battery life
+ Price
+ Works with most headphones
- Cannot charge while playing
Overall 9/10
[A/N - The amplifier was not tested with this IEM and this was only meant as an informative review. An amplifier is not needed for these if you already own a decent DAP]
The RE-400 cable (not removable)

2)Unboxing and accessories
The RE-400 comes in a rectangular shaped glass-like box. The inside of the box is cut for the individual pieces found inside, that is the headphone, 6 different tips (one comes pre-installed) a clip and that’s about it. The box itself is made from two pieces and these like to fall apart a lot. It doesn’t really hold together well and it really contains only the most basic things. Although they come cheap, a better box would be nice.
Update: Now comes with a nice hard-shell carrying case, more ear-tips and even two pairs of foam tips [all reflected in comfort/fit]. Packaging rating improved.
Package overall 8.5/10


3)Design, build quality and comfort
a)Design/Build quality
I am glad I can say that the build quality of the RE-400 is the best yet of all the HiFiMAN headphones. The headphones look finished and sturdy and could definitely take some abuse. The only issue I had was with the jack of the cable, which snapped, but this was mainly my fault and was briskly replaced with a different jack by my local dealer.
The cable is a bit kinky and likes to get stuck on clothing but is in turn rubberized and of nice quality.
I am definitely happy with the overall feel of these headphones, from top to bottom they feel like a well-made product.
The shells are made of aluminium and feel great in the hand. The cable, on the other hand, ...
Update: The [cable's] build quality unfortunately did not hold up to initial expectations. The shells are not to blame, they are made from aluminium and feel very sturdy the cable, however, is a different story. I had the jack break once and the internals of the cable [meaning the thin wires that are underneath the sleeves] are probably significantly damaged. I need to stress that I took very good care of the IEM, but the cable has a will of its own and it coils down all the town, which is probably the culprit of it. Still it is a thing worth mentioning and a nominal design flaw. I'll bump the build quality down by 3. 
Update 2: Since my inititial issue many months back, these headphones have been holding rather well, though the cable is still microphonic and tangly... I will boost the build quality up for now, assuming the teething problems have been fixed by now.
Build overall 8.5/10 (Build quality 8/10 Design 9/10)



Only one of the 4 stock tips fit me. They came preinstalled on the monitors. Changing the tips is not that hard but since I don’t have any other tips available right now, the stocks will have to do. They isolate quite well. Medium insertion seems best for sound quality and comfort, isolation. They fit in nicely so I can wear them for hours, adjusting here and there. I was worried about the fit a little, but everything seems ok. Decent comfort and fit.
Update: It now comes with more tips, including a two pairs of foam ones.
With them, the white middle-sized tips [pictures further down] currently offer the best comfort/fit ratio. I want to stress out that fit is really important for the overall balance and bass presence. Luckily, there're many tips included now, so finding the ones that fit shouldn't be a problem anymore.
Comfort/Fit overall 9/10
White Tips


Stock tips


4)First and further impressions
There wasn’t much burn-in with this IEM so to speak. Back then I still used my trusty Samsung Wave I (S8500). For now, there is no external amplifier to speak of. I am considering one for the future, as I will probably need one for the RE-600, which I’ll be buying (and subsequently reviewing) most likely. Initially, I was really surprised by how good the sound was. The vocals were butter smooth, midrange was full and lush, bass was nicely detailed, slightly lacking in depth and punch, but very nice. Highs were very smooth but still didn’t lack excitement. Soundstage width was great, extending even out of my head slightly. Instrument separation was still top notch like with all other HiFiMAN. I didn’t perceive any burn-in with these, really, other than changing my phone for a Galaxy Ace II.
They certainly didn’t disappoint.
First impressions overall 9/10
Update: I am now using a Sansa Clip+ and the RE-400 are great with it!
Update 2: I've now purchased the Fiio X1 and the RE-400 is simply stupendously great with it. I will change the review scores and corresponding sections slightly to reflect this marked perceived improvement. I am also using a different set of ear-tips, which come with them now [see pictures] and those give me nearly perfect seal. This, coupled with the X1
makes the RE-400 a seriously amazing pair of IEMs for the asking price.
+ Tight
+ Lots of detail
+ Non-intrusive
- Can be a bit soft at times
Overall 8.5/10 – The low-end of this headphone is pretty good, sounding pretty much tight and punchy, very much in line with the bigger HiFiMAN headphones. As such, it also bears the same relative shortcomings - coming off a bit soft in weight and punch at times, with a bit less oomph than I'd like. But the reward is that the bass always remains tight and in line with the other frequencies, never sounding overbearing but not sounding deficient either. The IEM is certainly potent and depending on the recording it can drop some serious bass, punchy and extended, but still controlled, mind you. Now that I've achieved a proper seal, I don't think the bass is lacking or weak anymore. Instead, it is just the traditional HiFiMAN signature bass I learn to really appreciate.
+ Balanced across
+ Natural and sweet
+ Instruments have their space
+ Pretty great detail retrieval
- None
Overall 9.5/10 – I don’t personally take any issues with the midrange. In many aspects, it is like a full-sized HiFiMAN lite. It lacks the ultimate spaciousness and air of the full-sizes, but it still offers an absolutely even instrument reproduction across, with a balanced but still dynamic sound. The midrange is slightly forward, just enough to keep its bite but smooth enough to not be fatiguing and providing hours on end of enjoyment. This is the area where this headphone definitely shines. 
+ Nicely extended
+ Sufficient presence
+ Absolutely non-sibilant
+ Clean
- Lacks some air
Overall 9/10 – The vocals work rather well for my tastes. They are present at all times, without ever sounding muted or constrained and still very much smooth and sweet. There is not a massive amount air but there is a enough to make this IEM sound more airy than most sealed headphones. They have a fair amount of extension, but not overly so and this contributes well to the smooth signature of the RE-400. These IEMs are not bright by any means, but they aren't dark either. Still, they play nice with everything I've thrown at them, producing a slightly warmer but still fairly neutral sound.
+ Natural
+ No added presence
+ Just enough extension
+ No harsh moments
- Lacks the last bit of extension and air
Overall 9/10 – The highs work the same way as the vocals and midrange. They are sufficiently extended with some slight roll-off to prevent them from ever sounding harsh with cymbals for instance but there is enough presence there to carry all the necessary information without overdoing it. Electric guitars never sound edgy either. Together with the rest of the frequencies they offer a smooth, balanced and forgiving experience ideal for traveling or relaxing at home or work. They do many things right without doing any obvious wrongs and as such they are hard to put down.
e)Soundstage/Instrument separation/Imaging
+ Great width
+ Stellar instrument separation
+ Smooth and even tonality
+ Plays nice with everything
+ Detailed
- Lacks depth and height
Overall 9/10 – As I said, the tonality of the RE-400 is very smooth, while offering great detail retrieval and musicality. Due to the tight bass, I wouldn’t recommend them solely for hip-hop or rap, though they still perform reasonably. These offer just a sibilance-free, engaging but relaxing experience. Basically a toned down full-size HiFiMAN in all aspects with some slight roll-off at both ends. The instrument separation is excellent and the soundstage width is likewise great. Center stage is very coherent and does not exhibit any oddities or unevenness and nor does the rest of the stage. The imaging is likewise excellent. 
f)Recordings sensitivity
Overall 10/10 – These belong among the more forgiving headphones for sure, and they're probably  the most forgiving “audiophile” headphone I have heard so far. I never had to turn the volume down with these because of harshness or sibilance. The interesting thing is that it still extracts a very fair amount of details and it does it really well without any obvious peaks or recesses, which usually isn’t the case with other headphones. HiFiMAN has managed to master the balancing act with these, offering great detail retrieval with a smooth tonality - something that is very hard to achieve.
Overall Sound
As such the RE-400 belongs among my favorite headphones - with tight and punchy bass, present mids and smooth and extended highs. Coupled with good detail retrieval, good soundstaging and remarkable imaging and separation, these fit right into my favorite sound signature, with very few minor imperfections that are easily forgivable based on the price/performance ratio these little puppies offer.
Sound overall 9/10
RE-400  N/A (I wouldn’t consider an IEM for gaming, really. Feel free to give it a try if you want though and report back :})
[HE-6 and Pro 900 have been reviewed for gaming, to see the games that I've tested and how those did, check their individual reviews on pages 1 & 6]
The RE-400 would be my top pick for portable headphones. It doesn’t really need any sort of amplifier to sound top notch. The signature also works really well when you want to focus on other things or just relax. Every song works here so you don’t have to worry too much about quality and specific playlists and as such it could very well be your perfect travelling companion.
Portability overall 10/10
8)Unique trait
The tonality of the RE-400 is one of smooth nature and rich detail. This tonality is particularly inviting to me because there are not all that many headphones with such traits. There is a bit less highs and vocals presence and bass than with the HE-6, making it similar enough in tonality but different enough in presentation. If you want a totally smooth pair of in-ear monitors this is the right one to choose. The RE-600 should offer similar tonality as well with more body and less roll-off at either end. W will soon find out 


9)Songs and genres
[see HE-6 Ultimate Review, page 1]
This was my very first serious IEM purchase. I was a bit skeptical about just how good such a tiny driverlike this one can sound. I was quickly reminded that at HiFiMAN they simply know what they are doing and how to produce top notch sounding products. Even in direct comparison with full-size offerings, this little fellow muscles up and certainly holds its own ground. It is not as extended or airy or spacious as its higher brethren but the price is much more feasible and honestly, an IEM just cannot sound that way. Still, for just around 100 USD you get a sneak-peak into the HiIFiMAN house sound. The performance was smooth throughout coupled with a highly enjoyable signature straight off your DAP's jack. I've tried an amplifier to see how much difference it would make, and there was none - the X1 just sounds phenomenal with these. As is, this headphone is simply too good to resist at the price point and everyone who is looking for a very decently priced, neutral-warmish IEM to get, you might as well pick this one up. You certainly won’t regret it.
Overall value 9.5/10

The joint point

This is a seriously good IEM, absolutely suitable for portable use. I am not a huge fan of IEM due to their inherent shortcomings [lacks the soundstage of full-sized headphones, etc].
I am one of the few who don't mind carrying around full-sized headphones, provided they are not difficult to amplify well.
Still the RE-400, being a bit of my IEM premiere, did not disappoint me and I sometimes prefer it to full-sized headphones when I want that smooth, detailed yet non-fatiguing sound.
For a hundred bucks, this is a great, great IEM, even though the cable could have definitely been better made, at least initially.
RE-400 final score 9/10
12)Special thanks: 
[See HE-6 Ultimate Review, page 1] 
Kindest regards and thanks to anyone reading this. Hope you liked it!
Luke, the reviewer
If Re-400 gets 9/10 soundstage, 9/10 treble scores, better ones should get 15/10 16/10 etc. hence your scoring is a bit too high for Re-400, even though I also quite like them.
The scores are relative to their price :]
"Also the very first IEM made by HiFiMAN."
Uh, no. HiFiMAN made dozens of other IEMs before the RE-400, but discontinued all of the legacy models when they released these. Great read, though. 


Headphoneus Supremus
Pros: bass decay , speed , details , clarity , instruments separation , top end spark , nice cable .
Cons: some veiling in the mids , bad cable clip , if that is a thing .
 i totally would like to believe that there is no earphone brand as admired as hifiman , at least admired by purists , and the small and cute re-400 is not an exception , its a total value phone and every penny is best invested .
 yes these phones lack some sub bass and dont hit big like a bass phone cuz its nothing close to it , it is more of a mid centric phone and is as balanced as i wish , now im not a fan of booming bass so i like re-400 more than S5 or ckx-9 , sound stage is good , i like it , good depth but narrow , vocals are a bit veiled thats all i can fault about , instruments are really clear and i love this highs , good energy and good extension , sonically these are awesome and extension in the top end is exceptional .
 i love it as much as my er-4p , and i think if re-400 were to grow up , it would have become an er-4p .
 a brainwavz S5 comparison can be found here . similarly priced but far more different in other things .
Agree with this review in that it's a very good earphone. I picked them up as a cheap spare but when I use them I am always satisfied. Not that one would normally do this but I tried them with a Bakoon HPA21 amp and the soundstage size expanded significantly, the size of all the instruments were bigger and there was significantly more bass presence. It's still not a bass-head phone but there was A LOT of bass with the HPA21. It's amazing how well it scaled up with high end amps. 
I was previously using RSA Predator, Geek Out and ALO International. They are no slouches either but the Bakoon was something else. 
that amp is like the best may be .