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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100+ Head-Fier
Watered down Hifiman
Pros: Good build for the price
Abundace of the tips included
Clean neutral tuning
Good timbre
Very good staging
Cons: Cable isn't replaceable
Bass might be lacking for most people
Treble could have been smoother and extended more
Hifiman is mostly known for their open-back planar magnetic headphones and I myself own 3 pairs. As you may already know, almost all of their headphone offerings have become benchmarks in their respective price ranges. Other than headphones, they make IEMs, digital to analog converters, amplifiers and digital music players which are more or less successful in their own right and this is a review of one such product: their bullet style IEMs RE-400.


RE-400 is their cheapest IEMs as of now and although the original price for it was 79.00 USD when it first came out, now it’s sold for 19.99 USD on their official site and Amazon.


Hifiman RE-400 was provided to me by Hifiman for free and I only paid for the customs fee. As I always say, everyone is biased one way or another so take everything you read with a grain of salt. Also I will try to be more concise and to the point in my reviews from now on without worrying about the word count etc. If you have any questions, please ask me in the comments and I will try to answer them to the best of my abilities.

Build and Accessories of Hifiman RE-400​

Shells of the RE-400 are bullet shaped and relatively small. Not as small as Final Audio E series IEMs, but still very comfortable. As materials used, they are made out of aluminum, not the smoothest aluminum out there, but still feels premium especially for the price.The cable which is fabric coated below the splitter by the way, isn’t replaceable and has some memory unfortunately. Cable termination is 3.5 mm single ended and angled.


RE-400 comes in a compact plexiglass packaging. It doesn’t look too cheap and they probably decided to increase the contents along the way since there is also a bag of accessories that comes with it. Apart from the IEMs, you get a carrying case and 8 pairs of different eartips. I mostly used double flanged ones in my testing.

Sound of Hifiman RE-400​


RE-400 has a neutral tuning, almost like an average Etymotic. It isn’t particularly devoid of bass but there is not too much of it to speak of. As a character, the bass is relatively fast and tight.


Mids are very clean and clear but also a little lean. Vocals mostly keep their distance. In this sense, RE-400 kind of sounds almost like their open-back planar magnetic headphones.

There is no harshness in the treble region but it also isn’t very smooth. There are narrow peaks you notice occasionally and treble extension isn’t great either.


The most impressive aspect of RE-400 is its staging capability. Stage expands sideways and it creates an interesting hall effect. In fact, it was the first thing I noticed as soon as I put them in my ears. Imaging is also pretty good.


RE-400 sounds kind of dry but other than that timbre is mostly fine, nothing jumps out as unnatural. Lack of extension kind of hampers the rendering capability but at this price, I won’t complain too much. As always comparisons shed more light to how RE-400 sounds.


Hifiman RE-400 vs Final Audio E3000​


Volume Matched at 1 kHz

  • E3000 is much warmer, has much more bass and subbass than RE-400. However, the E3000's bass is more pillowy. RE-400 isn’t really devoid of bass and it’s tighter.
  • RE-400 is much cleaner.
  • Vocals are more forward on E3000. RE-400 leaves room to breathe.
  • Neither is harsh. E3000 has a better treble extension but that might also be because of the deeper insertion it provides. RE-400 rolls off earlier in the upper treble.
  • RE-400 has a wide spacious sound and interesting hall effect. E3000 on the other hand, also has a very tangible staging and it feels like you are in the studio with the artists. Both have their stages expanding to the sides but RE-400 is wider. Imaging is very precise on both.
  • Personally I find overly warm iems suffocating. On that note RE-400 feels fresher for me.
  • Both have decent timbral qualities but RE-400’s timbre is more lifelike. E3000 warmth skews the balance a little too much.
  • E3000 renders more details but warmth drowns a big part of these details so RE-400 might come as more revealing to most.


Hifiman RE-400 vs Tanchjim Tanya​

Hifiman RE-400 vs Tanchjim Tanya​


Volume Matched at 500 Hz

  • Tanya is V-Shaped while RE-400 is neutral. Again Tanya is warmer but it also has upper mids presence so vocals are slightly more forward. Vocals on RE-400, although not too recessed, aren’t too close and personal either.
  • Bass on Tanya is also more impactful and extends deeper.
  • Although Tanya is shoutier, neither is necessarily harsh.
  • Treble on Tanya is noticeably better. It has good energy and is smooth at the same time; pretty much on point and it has better extension too. RE-400’s treble sounds blunted compared to Tanya’s.
  • Tanya’s timbre is objectively better but I find RE-400’s timbre somewhat more agreeable. Maybe Tanya's shoutiness affects my perception.
  • Tanya is more detailed by a good margin. Staging is extraordinary on RE-400. It expands wider than Tanya’s headstage but Tanya’s stage is deeper. RE-400’s imaging is also better.



I wasn’t expecting too much from the Hifiman RE-400 but I was pleasantly surprised. It doesn’t set the world on fire, no, however for the price now it sells, it’s hard to make an argument against it. Especially in a market that is flooded with V-Shaped and Harman tuned IEMs, it feels fresh with its clean neutral tuning and the interesting hall effect it creates. All in all, maybe not at the full price, but for 19.99 USD, I think RE-400 deserves a place in everyone’s collection.
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Pros: Perfect Neutral sound signature
Excellent mid-range clarity
Lots of great ear tips provided
Price is amazing at $19.99
Cons: Fixed Cable isn't great
Sub-bass was lacking especially when compared to 'Harman' IEM's

Hifiman-RE400 Review​


I would like to thank Mark from Hifiman for providing these IEM’s for this review

I came across this IEM maybe 10 years ago - it was then a steal at $99 for its then reference sound. But allot has happened in the IEM market in 10 years so has this ‘old dog’ still got tricks for the ‘young pups’ of the IEM market. And mostly importantly how does it sound stack up against its competition.

Original launch​

It can be funny to look back at old reviews for products that are still around, for example, here is Steve Guttenberg written Review(‘i.e. The Audiophiliac’) of the RE-400. The major complaints in this review and others from the original launch was the lack of a carrying case and a limited amount of ear tips. The price of the RE-400 at the time was $99 but unlike nearly every other bit of classic audio gear, the new RE-400 starts at an incredible $19.

Let’s see in detail how an upgraded RE-400 “waterline” stacks up - first lets have a look at what Hifiman now provides ‘in the box’:

Whats in the box:​

So looking at what we get now with the RE-400, never let it be said that Hifiman do not listen to their customers feedback as the “new” RE-400 addresses these issues mentioned above immediately once you open the box.

IMG_9026 Medium.jpeg

IEM and Cable​

While the IEM itself is tiny and cable is permanetly attached, which for $19.99 that is perfectly fine but obviously more expensive IEM’s now have detachedable cables unlike when the RE-400 was launched.
IMG_9071 Medium.jpeg


What I think is excellent is the sheer variety of sizes and even shapes of the ear tips provided and they have even provided some filter replacements. Different tips can have a massive effect on the sound profile and comfort of an IEM so having this variety is a massive benefit over similar priced IEMs.

IMG_9038 Medium.jpeg


For such a tiny IEM, the variety of eartips sizes can greatly effect the comfort. For me and my large ears, I found the largest ‘fat’ tip provided excellent seal and was very secure in my ears during a few long walks. I love how they provided angled eartips also which no doubt will suit some people.

Because it’s so small, it is incredible lightweight and mostly you can wear this for hours without any discomfort, it never feel out of my ear and it lack of weight greatly helped it stay in place compared to much larger IEM’s like the Truthear Zero (see photos later), my one issue with the comfort was the cable. I found it caused some microphonics as it rubbed again my clothes. I did change its position to around my ear which greatly helped but it is something to bear in mind.

My wife on the other hand has tiny ears she loved the size of the small tip and she has now taken the RE-400 as per favourite IEM’s for comfort and sound quality.

The difference is size can be seen in these 2 photos:

IMG_9069 Small.jpeg

IMG_9070 Small.jpeg

Sound quality​

So running through my long audiotext playlist - the RE-400 came across as very neutral, but does lack a little in the sub-bass region. As a sound signature, I thought it was more like the Etymotics ER2SR than the ER2XR, so bass heavy tracks like James Blake’s"Limit to your Love" didn’t have the bass punch you might expect coming from a Harman or V-Shaped IEM. But it more than made up with the with female vocal tracks - Kate Bush sounded amazing and Amy Winehouse had a liveliness that I have not often heard from IEM’s.

Midrange Clarity​

Midrange performance is exemplary, delivering vocals and instruments with a natural and lifelike presence. This midrange fidelity is a testament to the RE-400’s engineering especially looking at the size of the IEM it is hard to believe it can make such beautiful sound, appealing to audiophiles who appreciate a true-to-source experience. It actually sounds more like a Sennheiser headphone than a Hifiman.

Realistic Treble and Imaging​

High frequencies are handled with precision and without harshness, contributing to an extended and airy soundstage. This attribute makes the RE-400 particularly suitable for acoustic and vocal-centric genres.

Specs and Measurements​

The main specifications:
Frequency Response15~22 KHZ
Cable Length1.33m
Impedance32 Ohms

With measurements, due to its size this IEM especially will highly dependent ear tips and there objective measurements especially of bass and treble with vary greatly.

But I thought this might graph from Crinacle IEM comparison tools might provide a good match for what I heard from the RE-400, specifically compared to an classic Etymotic IEM:


As you can see both are incredible similar until the treble region where each manufacturer has their own unique take on treble. I personally like the RE-400 more, that boost in the 5-6Khz region provided excellent dynamics while to me was never fatiguing.


Here is a comparison of the sizes of some similar priced IEM’s, the difference in size is remarkable with the Truthear Zero Red on the left, the Moondrop Chu in the middle and RE-400 on the right:
RE-400-comparion Medium.jpeg

Sound quality wise the Truthear and Chu have more sub-bass both targetting that Harman curve but the RE-400 is much more balanced especially in the midrange. Basically if you want a reference IEM’s go for the Hifiman if you want a ‘fun IEM’ go for the Truthear. I would probably not recommend the Moondrop Chu due to its poor treble response, though its a similar price to the RE-400.


The Hifiman RE-400 is a remarkable contender in the in-ear monitor market. Its focus on delivering an accurate and balanced sound profile makes it a prime choice for audiophiles on a budget. While its non-detachable cable may not appeal to everyone, its sound quality undoubtedly places it among the top performers in its price range. The RE-400 is a testament to Hifiman’s commitment to high-fidelity audio, packaged in a practical and everyday use design.


New Head-Fier
Hifiman Re400 - The Tiny Monster
Pros: Just 20 USD for USA & Canada
Shell quality is good
Extra tuning filters
More comfortable than many others
Balanced tuning
Natural Bass
Good details
Pretty good image and soundstage width
Easy to drive (you don’t need anything expensive)
Cons: Fixed cable
Tips could be better quality
Slightly veiled voices
Cable is rigid and seems quite bad



The Hifiman RE400 were kindly sent to me by Mark of HIFIMAN, for which I thank you very much. I’m an old model (10 years of honorable service), probably in dismantling.

Nevertheless, every headset enriches my package of experience in this world.

Like all other reviews, this one will be honest and not influenced in any way.

Having received a boxless version this time, the unboxing opening will be skipped.

Hifiman RE400 Tech Specs:​

  • Titanium-Coated 8.5mm drivers custom designed by HIFIMAN
  • Compact size utilizing powerful Neodymium magnets
  • Oxygen-Free Copper Cabling
  • Advanced ergonomics for comfort and extended listening
  • Stylish design and lightweight
  • 3.5mm mini plug
  • Mini adapter for regular earphone jack
  • Frequency Response: 15Hz–22kHz
  • Impedance: 32 Ω
  • Sensitivity: 102 dB
  • Rated: 10mW
  • Weight: 0.45 oz (12.9g)

Hifiman RE400 Accessories:​

From the rush to try them, I must have missed some accessory, or maybe not being a store version has some less accessory. However, included in the sale box, you will find:

  • 7 pairs of tips
  • Replacement filters
  • A clip
  • Storage for transport

For the price requested to date, the standard equipment is quite expensive! The tips are definitely weird, from very small to huge, but I have to say that among all, I found my favorites.

Hifiman RE400 Design/Build quality:​


The Hifiman RE400 stands out at first sight for its extra-small size. They are so small that they almost disappear in many people’s ears. If you do not pay attention, you may lose them in the hearing canal! I’m kidding, of course! The shell is super miniaturized and made of fine CNC aluminum, but the cable is thin. In the first, it is coated but overall very rigid and looks undurable. In my case, I have a maniacal cure, so they will last forever anyway.

Initial sound impression:​

At first hearing, they seemed very veiled and frankly did not sound very well; maybe they came from a warehouse, but after leaving them in operation for a while, the situation turned.

Their sound was definitely different, better in every way, which was surprising given their size! I was already surprised by the sound of other microdrivers that I had found in the Kbear Dumplig, but these are on a very different level.

Since they probably really came from some storage remnants, I left them burn-in for 50 hours at high volumes.

Hifiman RE400 Final sound impression:​

Equipment used for testing above:


  • iMac
  • Redmi Note 7 (MIUI Based)

  • Foobar2000 24bit 192khz (iMac)
  • Amazon music UHD 24bit 96khz (Both)



Fortunately, in the tips included in the package, I found the double flanges that fit me like a glove, isolate me perfectly, and allow me to insert them in depth.

I’m not listing the tracks because they’re too many.

My impressions are given using the original accessories.

What makes significant improvements is deep insertion, so if you can’t find tips that work for you, look for double or triple flange ones.

I would never have imagined that such quality could be achieved with such small drivers.

The Hifiman RE400 is a balanced IEM with a touch of warmth. For what they cost now, they are excellent and also incredible. The tuning is smooth as ****!

The tuning is definitely free of annoying peaks. It might be boring to some, but it’s not terribly neutral either. In the bass region, there is definitely emphasis and good speed. The voices, however, are slightly veiled, perhaps a little nasal sometimes. The musical instruments have a coherent tone, but it is their separation that is most surprising. The highs maintain a very good amount of detail without ever being sibilant or harsh.

The thing that surprised me the most, however, is the total absence of distortion, even at very high volumes. They handle the maximum volume of my DACs like nothing.

Hifiman RE400 Soundstage and Imaging:​

Keep in mind that the soundstage is enveloping in width. Imaging is really good with a precise separation. Make sure to have a deep insertion, and you can feel the magic of this tiny titanium-coated driver. I have listened to jazz, R&B, pop, EDM, and chill music.


I thought I’d compare headphones that remain in the same price range. It goes without saying that the RE400 can compete in the price range at which it was released 10 years ago, even today.

vs Moondrop CHU II

CHU 2 + wide bore tips

The Moondrop CHU II is excellent, but the tuning is V-shaped, and the bass is very emphasized. If you are not into headphones that tend towards balancedness, then you are better off not looking at the Hifiman RE 400.

vs Tanchijm Zero and One

Tanchjim One Labeling 2
Less da1 + Zero

They have a certain resemblance to the Tanchjim Zero, but I would say that the Hifiman RE400 has a decidedly more pleasant and warm tuning. The Zeros are excellent for neutrality and detail, but their comfort has always been quite terrible. The One is slightly over budget but is worth mentioning and considering as they are also excellent. They have more pronounced bass and treble and a larger soundstage sensation.

vs Kbear Dumpling

Before trying these Hifiman RE400, they were my favorites extra small in-ears. The dumplings have a much warmer sound; the bass is dominant but also has less detail and a decidedly more nasal timbre. For about the same price, I would choose the Hifiman, but the build quality is better on the Dumpling.


At the new price at which the Hifiman RE400 is offered, it is definitely unbeatable. They have certainly gone out of production and are running out of stock. If we also consider their extra-small format, they are in an unrivaled category. If you have the chance, definitely get a pair! Not being too neutral, they adapt to every musical genre, and being so small, they fit practically every ear. A real taste of HI-FI without spending too much! The only thing they require is to be used with care due to their very weak cable, if you are clumsy you should avoid them.


Where to buy?

Official Hifiman Website



100+ Head-Fier
Just wanted to point out that these are now on sale at both Amazon and the hifiman website for $20. I personally slightly prefer the LG F-631 Quadbeat 3 "Tuned by AKG" for most uses (which is $15 on ebay, shipped from China), and I EQ the 2k bump down a little. I think I've been through 5 pairs of those over 3 years as I'm sometimes careless with my IEMs. However there are a couple of applications where I cannot EQ it, and I'd rather than these RE400 for those times.