HiFiMAN RE-400

General Information

The RE-400 Waterline by HiFiMAN is a premium quality, high-performance In-Ear Monitor (IEM) that sets the standard for others to follow. Featuring advanced ergonomics for superb fit, and premium materials such as Titanium Diapharagm, Neodymium magnet and OFC Copper cabling, RE-400 represents best-in-class performance and comfort.
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Latest reviews

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.
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.
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


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