Hidizs MD4 4 Balanced Armature Drivers

General Information

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Hidizs MD4 4 Balanced Armature Drivers HiFi In-ear Monitors​

-4 Custom-Designed BA Drivers
-4 tuning styles
-3-way crossover
-High-precision 3D printing straight acoustic sound tube
-Multi-metal body
-Premium cable braiding, quad-core silver & OFC wires
-Detachable 0.78mm 2pin gold-plated socket
-Click below & get the 10% off for the New MD4!

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Official Release Page at Hidizs

Latest reviews

Echalon

100+ Head-Fier
Hidizs MD4: Warm, well built all-BA IEMs
Pros: Soundstage is pleasingly wide
Good timbre
Effective switches (3 of the 4 settings)
Nice set of accessories
Build quality
Passive sound isolation
Cons: Cable is just OK
Pressure during ear insertion might bother some people
Firm connectors
A little BA tonality on Treble tuning (both switches down)
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The Hidizs MD4 is a 4 balanced armature in-ear monitor, released in 2022.

Hidizs recently reached out to me to ask me to review this set, asking for no editorial control at all, only that I post these non-affiliate links to purchase the MD4:

Hidizs store

Amazon UK

I was definitely intrigued, especially as I had my eye on these since buying the MP145. Credit to Hidizs for giving me the freedom to write freely. When you have faith in your products, you can trust them to speak for themselves.

Prior to my review sample of the MD4, the only Hidizs products I owned were the planar MP145 and single DD MS1. The MP145 really put Hidizs on my radar: With great timbre, technicalities and an amazing sense of space, it remains my favourite planar.



Going into this review, I had 3 main questions:

  • Did the MD4 have anything in common with the similarly priced MP145?
  • Would the 4 balanced armatures give a sufficiently rich tone, especially in the low end?
  • Could a set from 2022 keep up with the newer releases?


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The Opening Experience

The unboxing of the MD4 certainly gives the impression of a premium product. A smart and tasteful box opens to reveal the IEMs themselves. Subsequent layers of the package yield several sets of tips and a cleaning tool, then a storage box containing the cable.

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Before getting on to the IEMs themselves, I have to say that I found the accessories to be above average. Three full sets of tips (helpfully labelled as Vocal, Balanced and Bass), and a magnetic case that feels very premium. The included cable is sounds better than the average bundled cable, though is a bit thin. I did change to a premium third-party cable, which added a little smoothness and extension. The cleaning tool is nice enough if you use them, but also can be used to flick the micro-switches – more on those later.

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The MD4s have a metal body, with a pearl-effect inset on the faceplate. My set is black, but there are white and blue versions available. They feel solid and well made, and in my opinion look quite classy. The 2-pin connector on my set was a little tighter than most, but not to the point that a cable felt stuck. There is gentle contouring all around the shell, resulting in a very comfortable fit.

As far as I can tell, the MD4 is unvented. This results in pressure on the eardrums when putting in the IEMs, when using some types of tips (such as KB07). If you are sensitive to such things, that could be a dealbreaker, but it shouldn’t be a problem for most people.

The final feature I want to mention is the micro-switches. Each earpiece has 2 switches, giving 4 settings from bright to bassy. They feel solid and as well made as the rest of the IEM. I’ll talk about their effect later in this review.

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The Sound

My first impression was space. I had not expected the soundstage and separation to be standout features, but from the first moments I could hear the relation to the MP145.

The timbre was much better than I expected for 2 year old BAs. These really do sound musical. The tonality is quite rich for an all BA set, and almost never sibilant.

Another big surprise was the bass. Apparently 2 of the 4 BAs are dedicated to bass, and it really shows. These slam and rumble, with quick and textured bass.

The switches give some good control over the tuning. As far as I can tell, switch 1 cuts bass and switch 2 cuts mids. The effects are significant, giving 4 distinct tunings:

  • Treble tuning” With both switches off, the sound is bright but to me it sounds less natural than the other settings. It is also the only tuning that can sometimes be sibilant. This tuning is adequate, but the MD4 seems to be held back from its full potential.
  • Balanced tuning” (Switch 1 on + switch 2 off) gives a mild V tuning. With the bass to balance the treble, the MD4 starts to sound really good.
  • Powerful tuning” (Switch 2 on + switch 1 off) emphasises mids and vocals. It does so effectively, and loses the subdued quality of the Treble tuning. Another fun sound from the MD4.
  • Bass tuning” With both switches up, the sound becomes full and rich. It might be a little too full-bodied for trebleheads, but this is my favourite tuning.


Overall the MD4s sound very good, with the layering and space of a multi-BA setup but without the thinness and low bass that is often associated with all-BA sets.





Comparisons

The beautiful Audiosense DT600 is the closest driver setup I have to the MD4, with 6 BAs. The shell is lighter than the MD4, and even more contoured. The build is similarly excellent, though resin rather than metal.

I find the technicalities of the DT600 to be a half-step better than the MD4, particularly soundstage and layering. On the other hand the timbre of the MD4 is ahead of the DT600, and the bass is significantly more prominent.

The tuning of the DT600 is closest to the Treble tuning of the MD4, and it does that treble-forward style much better. For richer, bassier music, the MD4 is the superior choice.

Overall these two IEMs are both very competent, but will appeal to different listeners: If you want a gorgeous all-BA treble boosted IEM with great technicalities, the DT600 is a solid choice. Should you want an all-BA IEM that sacrifices some of the technicalities for timbre, versatility and bass, the MD4 is for you.





Another natural choice for comparison is the Hidizs MP145. In contrast to the 4 BAs and tuning switches of the MD4, the MP145 has tuning nozzles and a single planar driver. The reasons for this comparison are that both are tuneable IEMs from Hidizs with a warm, spacious sound.

Physically, the MP145 is significantly larger and heavier. It also requires much more power to drive well, like most planars. The MD4 is more forgiving of weaker sources, but does scale up nicely with a better source.

To my ears, the MP145 is simply better, so long as you have a powerful source. Rich, detailed, and wonderfully spacious. The only thing the MD4 possibly does better is layering.

Despite the win for the MP145 in sound, the MD4 does have some advantages: an easier tuning system, lower price, and it is much more comfortable for those with smaller ears or who don’t like heavier IEMs.



Conclusion

The Hidizs MD4 surprised me, and I have really enjoyed using it as my daily carry for the last week.

While not revolutionary, this 4 BA IEM stands strong against the competition. You could believe that there was a dynamic driver producing the warm tones and satisfying bass, and it is free of sibilance and BA tonality (except on the lackluster down-down “Treble” tuning). It feels like the little brother of the fantastic MP145.

While I would not recommend the MD4 to everyone, if you are looking for an IEM that has a choice of several warm tunings, has good timbre and technicalities, is well built and easily driven, and is both cheaper and lighter than the MP145, then this is a strong option.

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suicideup

New Head-Fier
Hidizs MD4 Review!
Pros: Clean, versatile sound signature.

Never sounded thin despite exhibiting an all-BA driver configuration.

Excellent tuning switch implementation.

Deep, thick bass (bass and warm config)

Fast transient decay.

Excellent resolution and technical performance (warm and treble config)

Airy, expansive upper frequencies (treble, warm config)

Excellent fit, comfort, and isolation.

Excellent build quality and visual details.

Excellent packaging and included accessories. Lovely!
Cons: Midbass bloat and muffled lower mids are present on “balanced configuration”.

Peaks and slight sibilance are present on “treble” config.

Instances of overlapping in separation and layering are experienced on “balanced” configuration.



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Hidizs MD4 Review!

Good day! After 5 days of casual and critical listening, here’s my written review for the Hidizs MD4. The mermaid sings, sort of!

video review here! :


Additional Note/s here:
  • I will be using the MD4 with the stock “balanced” configuration and compare the other modes from there.
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Disclaimer/s:
  • I don’t read and read FR graphs. I only use my ears, as how earphones should be used.
  • Hidizs sent this unit to me in an exchange for an honest, unbiased review. Rest assured that this review will do its best to devoid from any bias/es as much as possible.
  • The following remarks and observations shall be made and owned only by me.
  • No monetary compensation is/was involved before, during, and after the period of creation of this review.
  • Your mileage may (and always, will) vary.
================================================================================================================
Burn-in time: 4-8 hours per day, 5 days.

Source/s used:
  • -Hiby R3 Pro Saber
  • -Fosi Audio DS1
  • -Non-HiFi smartphone (Infinix Note 12 G96), PC.
  • -Local Files via Foobar, YouTube Music, Deezer, and Qobuz with UAPP.
IEM/Earbud/Setup configuration: stock small balanced eartips, stock cable, any form of EQ or MSEB off, 40-60% volume, low gain and high gain.

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Sound signature:
  • With the “balanced” configuration set, the Hidizs MD4 exhibits a balanced, mild-v shaped sound signature. From there, the sound varies depending on the switch you configure it with.
Lows:
  • The lows are slightly elevated and are a bit midbass focused. Despite being an all-BA set, the bass exhibits a slightly softer than usual character to it, but still shows a good amount of articulation and speed. No matter what genre you listen to with this IEM, the Hidizs MD4 is able to cater most tracks easily, particularly in the bass department. There is a midbass bleed present in this configuration, which leads us to the mids.
Mids:
  • … is quite caved in , recessed, and sounds “off” which makes the mids not as extended and forward the way I prefer in this configuration. This is because of the midbass bleed/bloat smearing onto the mids. In return, lower mids are thick, muffled, and somewhat “boxy”. Male vocals seem to be sounding thicker than usual in this configuration. Upper vocals are slightly elevated in this configuration, exhibiting a good amount of clarity and sparkle. There are some instances of occasional peaks here and there, but nothing too off-putting for me to call it sibilant, strident, or hot.
Highs:
  • The highs are fairly extended, elevated, with a good amount of air. It isn’t as extended compared to the other configurations. Instances of sibilance in this region are non-existent in this area, but I am aware that there are other inputs experiencing some sibilance in this area, so do take note of those inputs as well if your ears are sensitive to upper frequencies. Detail retrieval in this configuration is average and is improved on other configurations.
Soundstage, Imaging, and separation:

  • The MD4’s technical performance is average in this configuration and gets better on the other configurations. Its soundstage aimed for a more “pseudo-immersive” one rather than your usual wide soundstage due to its height and width nearly having the same depth. Separation and layering are mostly good for the most part, with some instances of overlapping on some heavy passages in this configuration. Imaging is precise and is able to render instrument and vocal positions clearly.
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Other Driver Configurations! (U = UP, D = Down)

  • “Warm” Configuration (DU)
    • This by far is the best configuration among the 4 in my opinion. Everything is much more extended, open, clean, and airy. The boxiness of the lower mids are also non-existent in this configuration. Resolution is also noticeably better and microdetails are much more heard in this configuration.

  • “Treble Configuration” (DD)
    • Flattens the bass and extends the treble even further by making things more airier than usual. Bass is more tight, faster, and controlled in quantity. The bloat is also non-existent in this configuration, but some upper mid peaks are more apparent in this configuration. Technical performance here is identical to the warm configuration. Personally this is my favorite configuration, but most people will prefer the “warm” configuration.

  • “Bass Configuration” (UU)
    • Extends and elevates the bass even further, making things more rumbly. The bloat is slightly present in this config, but is definitely shaved or trimmed down compared to the balanced configuration. The rest are more or less the same.

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Pros:
  • Clean, versatile sound signature.
  • Never sounded thin despite exhibiting an all-BA driver configuration.
  • Excellent tuning switch implementation.
  • Deep, thick bass (bass and warm config)
  • Fast transient decay.
  • Excellent resolution and technical performance (warm and treble config)
  • Airy, expansive upper frequencies (treble, warm config)
  • Excellent fit, comfort, and isolation.
  • Excellent build quality and visual details.
  • Excellent packaging and included accessories. Lovely!
Cons:
  • Midbass bloat and muffled lower mids are present on “balanced configuration”.
  • Peaks and slight sibilance are present on “treble” config.
  • Instances of overlapping in separation and layering are experienced on “balanced” configuration.

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Verdict

The Hidizs MD4 is a very good option if you are looking for a very good sounding IEM with tuning switches under 200 USD. Its versatile, all rounder sound makes it really good for most genres you pair with it. By far, the “warm” setting will suit most listening experiences as it balances both tonality and technical performance evenly, while removing the bloat on the lower mids. Not to mention its very good technical performance for its price on most of its configurations. Hidizs did really well on this set, and I am open to hear more improvements of their works in the future. I’m impressed!
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Pairing recommendation/s:
  • Source: This IEM is very easy to be driven, and prefers neutral source.
  • Eartips: Eartips included are soft and good in quality, but you may always use your preferred eartips.
  • Cable: Cable is as good and basic as it gets. You may use your preferred cable as always.
Thank you for reading!

Additional Photos here:


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o0genesis0o

Headphoneus Supremus
Hidizs MD4 - Resolving and Immersive
Pros: - Very good resolution
- Very good soundstage imaging
- Multiple tuning options to match your unique ears and library
- Good accessories, particularly the classy carrying case
Cons: - The default tuning does not leave a good impression (to me)
- The Midrange is still slightly unnatural due to the 1.66kHz dip
- Barely adequate bass performance
- The stock cable can be very annoying
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Beyond tonality, what makes a pair of IEM or headphones "good"?

For some of us, it's all about that bass. For others, it's all about "timbre." Personally, I look for the elusive "resolution" and "soundstage." Whilst good tonality is getting cheaper with every new IEM, the same cannot be said about resolution and soundstage. Can Hidizs MD4 change that? Let's find out.

Summary for casual listeners: MD4 is a customisable IEM that sounds relatively pleasant and natural. It is good at separating elements of a recording and placing them around an imaginary sound "stage" around your head. MD4 is well suited for recordings with a sense of space and a lot going on (e.g., orchestral music, soundtracks, and some forms of electronic music). It is not suitable for genres that require a lot of bass.

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Forewords


  • This review is based on a review sample sent by Hidizs (Thank you!). I treat review units as long-term loaned units, meaning I can use them, but they still belong to the manufacturers.
  • I rate IEMs by A/B testing them against a few benchmark IEMs, regardless of price point. If a $1000 IEM scores the same as a $100 IEM, then either the more expensive one underperforms or the budget one is a gem.
  • I believe that great IEMs are the ones that can achieve multiple difficult things simultaneously: (1) high resolution (meaning lines of music are crisp, clear, easy to follow and full of texture), (2) 3D soundstage with a strong sense of depth, (3) bold and natural bass with a physical rumble, (4) natural timbre, (5) relaxing and comfortable tonality. IEMs achieving those criteria are rated highly in my ranking list
  • I use frequency response measurements to double-check my subjective impressions.
  • Ranking list and measurement database can be found on my IEM review blog.

Non-sound Aspects


In the box:
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Earpieces:
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The size of MD4 is above average. However, the earpieces are not as large as I imagined when reading others' reviews. The body of the ear pieces is noticeably thicker than Aria, roughly the same size as S12, and a bit smaller than Blessing 2.

The nozzles of MD4 are average in both diameter and length. They are not chunky like Blessing 2's or short and stubby like S12's. However, they are too large for deep fitting, so the earpieces do not fit snuggly against my conchas like a few other IEMs, such as Monarch Mk2 and Meze Advar.

MD4 earpieces are fully sealed, so you can have a vacuum-like feeling in your ears when putting the IEMs on. On the plus side, the noise isolation is above average, though far behind deep-fitting IEMs from Etymotic and Westone.

I find MD4 average in terms of comfort and usability. I primarily use these IEMs for commutes and daily walks as they are stable, effective in blocking noise, and easy to put on and remove.

Cable and connector:
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I can't say I am a fan of either the connector or the cable. The 2-pin connectors used by MD4 are not recessed (best) or flushed against the shells (meh) but popped out from the shells similarly to 64 Audio universal IEMs. I'm not too fond of this design because it can place a lot of pressure on the metal pins. I fear I would snap off the pins and get them stuck in the connectors. Still, nothing has happened, and the connectors seem durable so far.

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The cable is soft and good-looking, no doubt. However, it has three issues at once:
  • The QDC-like connector at the 2-pin side. These angled 2-pin connectors are annoying with KZ/CCA IEMs, 64 Audio IEMs, and MD4.
  • The pre-formed ear hooks have a very aggressive angle. They wrap tightly against your ears and curl around themselves when not being used (see the photo above).
  • The braiding of the cable makes it curl around itself automatically (see the photo above). This braiding is also used with ALO (campfire audio) cables and a cable from Dunu. I'm not too fond of any of these cables due to how tangly and generally unpleasant they are to use.

In the end, I tamed the cable by removing the ear hooks and stretching and twisting the cable until it softened.

Tuning switches:
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MD4 has two switches at the back. They are not simply "treble" and "bass" switches but have a noticeable effect across the entire frequency response of MD4. If you are curious, I have a detailed breakdown of what these switches do base on measurements at the end of this article.

For simplicity, I would use two numbers to denote a switch configuration in this article. For example, "11" means both switches are switched to ON.



How it sounds


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Listening tests were done with the following source chains:
  • (For A/B test) Android Phone / iPad Pro (Apple Music, Hiby App, YouTube) =(USB-C)=> Fiio KA3 =(3.5mm)=> Hidizs MD4
  • Android Phone / iPad Pro (Apple Music, Hiby App, YouTube) =(USB-C)=> Hidizs S9 Pro =(3.5mm)=> Hidizs MD4
  • Hidizs AP80 Pro-X =(3.5mm)=> Hidizs MD4
  • Nintendo Switch => Creative X1 => Hidizs MD4

Local FLAC files ripped from CDs or bought from Qobuz, and Apple Music Lossless were used for most casual listening and A/B tests. My test tracks can be found on Apple Music here.

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Tonality and Timbre: 3.5/5 - Above Average


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Frequency response of the "bass" configuration of MD4, which I used for all of this review. Measurements were done with an IEC-711-compliant coupler and might only be compared with other measurements from this same coupler. Visit my graph database for more comparisons.

When I saw the graphs of Hidizs MD4 for the first time, I was immediately interested due to their noticeable dip around 1.5kHz. This kind of dip appears in 64 Audio Trio, one of the most spacious IEMs I have heard. However, this tuning trick is a double-edged sword that can make an IEM sound hollow and unnatural. How well does Hidizs execute this tuning?

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Midrange: My first impression of MD4's sound was not positive. In the default tuning ("balanced"), the IEM sounds unbearably stuffy and boxy. Vocal such as Ed Sheeran's in Shiver sounds dull and muffled. Not warm, but muted.

The culprit was the excess energy in the lower Midrange (250Hz to 500Hz) that created a "veil" all over the music. The ear-gain region was barely enough to pierce through the "veil". With some brain burn-in and suitable music, such as "Father and Son" by Cat Stevens, this sound signature might be desirable or even charming to some, but not for me.

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Luckily, the tuning switches of MD4 bring about noticeable differences. The "treble" tuning (switch configuration 00) completely lifts the "veil" and extends the soundstage in all directions. In this configuration, the ear gain is pushed to around 13db above the lower Midrange, making it easy for midrange elements to cut through the mix. However, the strategic (accidental?) dip at 1.66kHz and 3.5kHz prevent MD4 from sounding in-your-face or piercing. Harsh recordings such as Shivers by Ed Sheeran are borderline shouty with MD4, similarly to Blessing 2 and other IEMs with Harman-inspired tuning.

If the "treble" tuning is too much, you can try the "warm" tuning (switch configuration 01), which flattens both the bass and treble by a couple dB. I find this sound signature closest to a "well-tuned" sound. However, the dip at 1.66kHz is not as pronounced, so the immersive soundstage imaging of MD4 is somewhat diminished.

My favourite tuning of MD4 is the "bass" tuning (switch configuration 11). It keeps the overall tonality of the "warm" tuning but brings the 1.66kHz dip back and reduces the ear gain just a touch more. The result is a pleasant, mostly natural, and spacious midrange. I say "mostly natural" because some vocals are still ever-so-slightly nasally.

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Treble and air: Well done across all configurations. Sparkly and resolving, but not harsh or piercing. Cymbals and hi-hats cut through the mix but do not stab the ears. This effect might be due to the strategic dip around 6kHz.

The "air" frequencies of MD4 are competent but not outstanding. You can hear airy reverbs and decays around musical notes. However, the energy level in the air region does not reach the level of top performers, such as 64 Audio IEMs with TIA drivers.

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Rating: Beside the boxy tuning of the default configuration, MD4 generally sounds natural and pleasant. The existence of the 1.66kHz, deliberately or not, adds a sense of spaciousness to the Midrange without making it hollow. However, I did need to jump through some hoops to reach that sound. Therefore, I knock half a point off the tonality of MD4, giving it 3.5/5 - Above Average.

Percussion Rendering: 3/5 - Adequate


Percussion rendering reflects how well the tuning and technical performance of an IEM work together to recreate realistic sound of a drum set. Good drum hits have a crisp attack (controlled by frequencies from 4kHz to 6kHz), full body (midbass frequencies around 200Hz), and physical sensation (sub-bass frequencies around 50Hz). Good technical performance ("fast" driver) ensures that bass notes can be loud yet detailed. IEMs that cannot control bass very well tend to reduce the bass' loudness to prevent muddiness.

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MD4 has the typical bass response of BA woofers and sounds quite similar to Campfire Audio Andromeda 2020. This bass response lifts the region below 1kHz by around 5dB rather than having a distinct bass shelf from 250Hz. It means that the bass of MD4 sounds like a large "boom" rather than a tight and deep "punch".

Is this bass tuning wrong? Not really. Because bass notes tend to disappear faster with BA woofers, the bass response of MD4 still feels clean, snappy, and relatively impactful.

Let's dig into some test tracks to see how MD4 compares against benchmarks:

Dragonborn: MD4 produces a bit of rumble at the beginning of this epic soundtrack. Throughout the piece, it manages to reveal the tempo and rhythm of the underlying bass line. However, the drums lack grip and texture. They sound "boom" or "poof" rather than "brrrm". This lack of texture makes this soundtrack a bit mushy, as it has a lot going on in the bass region. It should be noted that my Moondrop Blessing 2 (3.5/5 - Above average) is no better in this regard. MD4 and Blessing 2 are easily outperformed by a fully-powered FF3 (4.5/5) or E5000 (5/5).

Despacito: The first bass notes at 0:10 are soft and smoothened on both MD4 and Blessing 2. However, MD4 lacks the large and sudden volume swing that Blessing 2 can create at the first bass drop at 1:05. Both MD4 and Blessing 2 lack the bass texture and top performers like FF3 and E5000.

Based on the above comparison, it is clear that MD4's bass is adequate for casual listening. Drums are rendered with decent weight and body compared to ruler-flat IEMs like ER2SE (2/5 - Not good). However, the bass is inadequate for folks who are picky about bass performance or require a lot of bass in their music. Therefore, I rate MD4's percussion rendering 3/5 - Average.

Resolution, Detail, Separation: 4.5/5 - Very Good


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Resolution is a strength of MD4. Even with the less-than-stellar default tuning of MD4, I was still intrigued by how crisp and separated the IEMs render busy music. A/B tests against my benchmark IEMs further intensified rather than diminished my initial impressions.

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Let's dig into some test tracks and see how MD4's resolution compares against Blessing 2 (4/5 - Good) and Andromeda 2020 (5/5 - Excellent):

G.O.A.T. by Polyphia: The difference in overall clarity and separation between MD4 and Blessing 2 is quite shocking in this track. MD4 sounds crisper, more precise, and more separated throughout the whole track. At the same time, Blessing 2 is splashy, blurry, and even congested when the music becomes busy. The contrast between closer and further away sounds is obvious with MD4 but ambiguous with Blessing 2.

Andromeda is still half-step ahead of MD4. "Effortlessness" is the key word here. Despite sporting a "thicker" tonality, Andromeda allows you to follow individual elements of the mix with little effort. In back-to-back A/B tests, MD4 feels a bit softer, less crisp, and less separated than Andromeda.

Summer by Janine Jansen and friends: MD4 again sounds noticeably crisper and more separated than Blessing 2. Even though Blessing 2 is no slough by itself, back-to-back A/B tests highlighted blurrier note attacks, more congestion, and surprisingly more grainy violin sound.

Again, Andromeda is still half-step ahead of MD4. Back-to-back A/B tests show that every instrument on MD4 has a little less detail and texture than Andromeda. The gap exists even when I boost the volume of MD4 to a loud level to take advantage of "louder is better".

Synchro (Bom-ba-ye) The hand claps at the beginning is an excellent test for the micro-details, treble resolution, and "air" of an IEM. MD4 passes with flying colour, revealing more nuances in the claps and slight reverbs and decays at the end of the claps. Blessing 2 is splashier and not as crisp. Is the difference day and night? Not really. Because MD4 and Blessing 2 are resolving IEMs, distinguishing nuances like micro-details requires careful listening.

MD4 vs Andromeda is ... interesting in this test track. The slight "air" and reverb in the clapping section are better (!) on MD4. Still, Andromeda separates the individual claps a bit clearer.

Based on the above comparisons, I rate MD4's resolution 4.5/5 - Very Good. It soundly outperforms my Blessing 2 and just half-step behind my Andromeda.

Stereo Imaging (Soundstage): 4.5/5 - Very Good


Stereo imaging or "soundstage" is a psychoacoustic illusion that different recording elements appear at various locations inside and around your head. Your brain creates based on the cues such as the loudness and phase differences between the left and right channels. Most IEMs do not differ significantly, nor can they compete with headphones or loudspeakers. However, some IEMs offer a more spacious soundstage than others. Best IEMs can create multiple layers of sound from closer to further away and make some instruments float slight above your head.

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The soundstage imaging capability of MD4 depends significantly on the tuning configuration. To my ears, the default "balanced" tuning creates a tunnel-like soundstage: narrow but deep. This kind of soundstage reminds me of Fiio FA7s, which I found "uncanny". However, some folks find FA7s to have a massive soundstage, so the "balanced" tuning might work.

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To get the most out of MD4, I recommend either "treble" or "bass" tuning. The "treble" tuning opens up the soundstage in all directions. The "bass" tuning - my favourite- shrinks the soundstage a touch compared to the "treble" tuning. However, it brings the 1.66kHz dip back, which works wonders in tricking my brain into thinking that sounds come from different distances or "layers" in the soundstage. I crave this "3D" effect.

Let's dig into a test track:

G.O.A.T. by Polyphia: MD4 does this soundtrack justice. Sounds pop up from all directions in the 270-degree cone in front of me. Some effects even pop up from slightly behind my ears. The sense of contrast in terms of distance is immense: some sounds are right next to my ears, whilst some blips and blops fade away in the background as if they come from the room. Back-to-back A/B tests show that Blessing 2 is flat, congested, and lacks the sense of 3D that MD4 can create.

Can MD4 challenge Andromeda's famous "holographic soundstage"? Nearly there. Both IEMs are neck-and-neck in terms of placing instruments on the stage with pinpoint accuracy, not just left to right but also closer to farther. However, I still think Andromeda is half a step ahead of MD4. The extra 8kHz energy of Andromeda helps with creating the illusion that cymbals and hi-hats come from above. Andromeda's more modest ear gain also makes the illusion of depth a bit more intense and convincing.

MD4_5.JPG


Based on the comparison, I rate the stereo imaging of MD4 4.5/5 - Very Good. I want to emphasise that this score does not mean that MD4 has the largest soundstage (that honour goes to Sony IER-Z1R). What MD4 does in that soundstage is what makes it great: Sound is rarely congested but layered from closer to further away with a clear contrast between near and far.



Conclusion


What makes an IEM "good"?

For me, it's all about resolution and soundstage imaging. Hidizs MD4 is unique because it achieves both at a modest price tag (in the "audiophile" world. It is still an expensive toy in the grand scheme of things). Sure, the bass performance takes a hit, and the tonality is not quite "audiophile-approved". However, if you crave that resolving and "3D" sound, MD4 receives a recommendation from this reviewer.

Pros:
- Very good resolution
- Very good soundstage imaging
- Multiple tuning options to match your unique ears and library

Cons:
- The default tuning does not leave a good impression (to me)
- The Midrange is still slightly unnatural due to the 1.66kHz dip
- Barely adequate bass performance

MD4_summary.jpg


Appendix: What exactly do tuning switches do?


The left switch controls the frequency from around 1kHz. Turning it on dips this region by approximately 2dB and introduces a significant drop at around 1.66kHz.

MD4_graph_10.png


The right switch controls the whole frequency response. Turning it on flattens the curve below and above 1.66kHz, making the dip less noticeable.

MD4_graph01.png
Last edited:
C
Carpet
Good review and great breakdown of exactly what the tuning system does. Diagrams on resolution/attack/decay and soundstage were also illustrative of concepts that get frequently thrown around and often misused.
Ichos
Ichos
Great!

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