Hidizs MD4 English Review


Organic Technique




Construction and Design




  • 4 tunings for the same price. Plus extra tuning with the various tips as standard.
  • Organic and analytical sound, a good mix.
  • Great presence of all bands, generating a sensation of a wall of sound, full, wide, ample, solid, complete and musical at the same time.
  • Remarkable definition, resolution, clarity, transparency, separation and amount of air.
  • Very good packaging and quality of accessories.
  • Great relationship between design, construction, beauty, ergonomics, level of fit and isolation.




  • Different and daring tuning.
  • Cable with balanced connection cannot be chosen.
  • Pushed to the limit (high volume and bass-saturated music), the low end may suffer, generating a certain feeling of distortion.


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There is no doubt that Hidizs (the well-known audio brand founded in 2009 by Tamson) follows a straight and determined path. It became famous for pursuing the best quality/price ratio in its DAPS, seeking as an absolute premise, the best sound, thanks to its professional audiophiles in its R&D department. After a few years and with several models under their belt, they thought of creating IEMS as well. Until the present day, this progressive development has led them to present the model that I am now going to analyse. It is the Hidizs MD4. As you can see from its name, it is an IEMS with 4 BA drivers designed and customised by the brand itself. They have a double switch to select 4 different tunings and a 3-way frequency divider. The body is made of multi-metal. It has a high precision 3D printed straight acoustic sound tube. It is fitted with a high quality 4-strand cable with silver and OFC wires on a 2Pin 0.78mm gold-plated connection. It is available in 3 beautiful colours, black, white and indigo. Its outer face exhibits a marbled pattern to match the body colour. Naturally, Hidizs accompanies the set with a careful staging, packaging and quality accessories to elevate the premium feel of the product. Let’s take a look at the rest of the qualities of this great product.





  • Driver Type: 4 BA drivers designed and customised by the brand itself, 2 for bass, 1 for midrange and 1 for treble.
  • Frequency Response: 20Hz-40kHz
  • Sensitivity: 102±1dB@1kHz
  • Impedance: 8Ω @1kHz
  • Power rating: 3mW
  • Construction: Aluminium alloy body, CNC fabricated; rose gold centre frame, handmade celluloid faceplate, aluminium alloy output nozzle.
  • Jack Connector: 3.5mm SE
  • Capsule Connection Type: 2Pin 0.78mm gold plated.
  • Cable: Four 4-strand mixed braid, 2 strands made of high purity silver wire and 2 strands made of OFC wire.
  • Cable length: 1.2m in length.
  • Approximate weight: 14±0.3g, excluding cable.





First, I should comment that the colour of the reviewed model is black. The box matches this colour and is an almost cubic package, which on its upper side shows a realistic photo of the capsules, with the cable in place. Its dimensions are 125x125x92mm. In the upper left corner is the Hidizs logo inscribed in gold. At the bottom left is the model name and a short description. At the bottom right is the Hi-Res Audio logo. On the back side there are two columns: the left column is written in Chinese, the right column in English. You can read the specifications, the contents of the box, a schematic with the position of the switches and their corresponding frequency responses, and the brand’s markings.
When the box is opened, the capsules are encased in a dense, black foam mould, lined with a dark cardboard cover with the model name and a slogan inscribed in gold lettering on the bottom. Once this first layer is removed, there is another mould containing three sets of silicone tips and a tool for cleaning and moving the switches. The third layer consists of a square box, with rounded corners, made of brown leather, on the top of which is the brand’s seal. The complete contents are as follows:


  • 2 MD4 capsules.
  • 1 x 2Pin 0.78mm cable and 3.5mm SE plug.
  • 1 brown leather carrying case.
  • 3 pairs of white silicone tips, with vocal enhancement.
  • 3 pairs of black silicone tips, with bass boost.
  • 3 pairs of white silicone tips with black core, balanced.
  • 1 cleaning brush.
  • 1 user manual.
  • 1 warranty card.
  • 1 explanatory card with the modes of the switches and their FR.


What I like about Hidizs is that they design a compact packaging with a great content, a high quality and very attractive box, as well as 3 pairs of silicone tips, which allow you to fine-tune the sound of the MD4 even more. I can only miss some silicone tips, to be very strict.



Construction and Design


It is clear that the entire design and manufacture of each capsule is complex and laborious. Starting inside, there are 4 BA drivers customised by Hidizs. Two are dedicated for the lower range, one for the mid-range and one for the upper range, up to an extension of 40kHz, resulting in a Hi-Res certified sound. The internal audio transmission structure has been redesigned to house the drivers. A straight, high-precision 3D printed acoustic sound tube ensures a continuous and clean audio output. The entire body allows for increased sound effectiveness, reducing distortion and magnetic resonance. Each capsule incorporates a precise 3-way frequency divider, which helps to harmonise and balance each sound range.
Two micro-switches allow 4 different tunings to be achieved, enabling quick switching between high and low impedance.
The external construction of each capsule consists of 4 parts. A handmade, laser-cut and hand-polished celluloid outer plate with a marble/amber finish. The centre frame is a CNC machined piece of gold-coloured, rose-gold aluminium alloy. The output mouthpiece is also made of aluminium alloy and the body is constructed of EU IIA certified medical grade resin for the skin.
The shape of the outer face of each capsule is the classic African continent silhouette with stylised apex. Both the outer plate and the inner body are black on my model. The metal parts (outer rim and mouthpiece) have a golden-pink colour, which I prefer to call golden champagne. The IEMS are not very big, rather medium-sized, but their body has a thick rim, which houses the micro switches. In the space between them and the plastic base containing the 2Pin 0.78mm connection, next to the frame, you can read the brand name and a mole indicating the channel in white letters. The inner side is smooth, with a soft micro-sandblasted surface, no holes and an ergonomic shape, but with very light protrusions. The aluminium alloy mouthpiece has three levels, a small initial ring, a narrower and longer central cylinder, a slightly larger outer ring. The largest diameter is 6mm and the smallest 5.4mm. The protective grille is also made of metal and has micro-holes.
The cable has the classic Hidizs parts and is the same as the MM2 model. The 2Pin connectors of the cable protrude on a smooth surface, consisting of a translucent, angled sleeve. Each sleeve has a coloured dot (red or blue) to identify the channel. The cable, up to the sleeve, is made of two coiled strands and is sheathed in a semi-rigid, transparent plastic, which gives it an over-ear shape. The jack connector is the same as the cable of its siblings MM2 and MS2. The plug is 3.5mm SE gold-plated. The connector sleeve that covers it is a 19.5mm long cylinder with a diameter of 9mm, which is made up of 4 pieces. The first and closest to the connector is black, almost 14mm long. Then there is a beautiful copper ring, just over a mm long. Again, there is another black cylinder, on the inside of which is written the name of the brand. This piece is not movable and does not rotate. Finally, the top ring is again copper, in a colour that I like much better than gold. The dividing piece is simpler and is a relatively small black metallic oval piece. The pin has a similar shape, but is half as small and is a pinkish copper colour, like the pin sleeve parts. It is worth noting that the pin does its job perfectly and allows the cables to be fixed without slipping out of place unintentionally.
The cable consists of high-purity oxygen-free copper (OFC) and high-purity silver wire, stranded from 60 wires respectively. They all form 4 coiled strands, with one pair being a dark golden colour, while the other is more silver.
On this occasion, the design is somewhat more classical in its form, but not in its content. I think both the internal and external design are excellent, very neat, very beautiful and attractive. All three colours look highly elegant and I like them all. My only drawback is that such a nice cable does not have a balanced plug.



Adjustment and Ergonomics


A more classic shape contributes to simpler ergonomics that are also more proven and efficient. Hidizs returns to a semi-custom design with a medium size, smooth and soft inner body, with hardly any protrusions or anchorages. The mouthpiece is medium and a deeper insertion could be assumed, but the diameter of the mouthpiece prevents this, unless other tips on the market are used. With my large foam-filled tips, I get a very high seal, a very firm and durable fit, and a very occlusal fit that promotes great isolation. The rotation is small and the firmness is high, the set is suitable for daily and outdoor use, it is very insulating.







I have to be honest and say that I found the graphs a bit strange. It is a two-zone profile, almost split at 2kHz. The first half is a rounded curve, slightly excited in the mid-bass. The level of sub-bass will depend on each tuning, as well as the linearity of this half. Before reaching 2kHz there is a valley which is more or less pronounced, depending on the position of the switches.
The second half starts with a double-peaked growth curve towards the high-mids and first treble, and then gradually and smoothly descends towards the inaudible high end.
The jump between the first and second half is very obvious and large in dB, augmented by the valley just before the jump in some tunings. Not so big is the downward jump after the first treble. Actually, this upper zone is quite common in all tunings and what changes is the emphasis on the rest of the curve. You could take the 10kHz as a junction reference and in that way you could see, perfectly, the differences of each profile. And this is what the frequency responses actually offer. Between one tuning and another there is not only a change of profile, but also a change of volume, as a result of the change of impedance that the switches generate.
All these characteristics led me to expect a rather polarised sound. Well, the final mix is better than the graph shows. But, it is true that it is not a common tuning, at least, from my point of view. But I can’t give a profound opinion either, because I am only a reviewer, not a tuner.
Here is the result of my measurements and the comparison provided by Hidizs.



It’s difficult to decide on a tuning. As a good bass-lover I always tend to start with bass tunings. I find that it can satisfy me on occasion, but I find an emphasis on mid-bass beyond my preference. I tend to lean towards a higher sub-bass boost and a cleaner, descending mid-bass. On the other hand, this is not an obscure tuning, and the MD4’s profile is quite technical, with a certain analytical edge. Without losing too much bass, but linearising the area and the transition between the first and second half, the warm tuning is the one I have used the most. It is not without clarity and I think it has the best overall balance. The treble tuning is also consistent and will be the best technical level of the ensemble. Whereas I find the balanced tuning blander and the valley between parts more pronounced.
Most of my impressions have been taken with the warm tuning, unless otherwise specified.




The Hidizs MD4 uses a dedicated dual BA driver for the low end. Its profile is biased towards the mid-bass and, although it has depth, the incidence of sub-bass is not very pronounced. Generally speaking, BA drivers tend to colour the bass response, giving rise to a different vibration than a dynamic driver. In this case, this statement is still quite valid. The sub-bass is produced as a coloured oscillation. But the 40Hz point sounds fairly realistic. From this point on, the pure tones return to the BA sound I am familiar with. You can’t judge a BA driver, two in this case, by the pure tone test. But it is a test to visualise its performance and realism.
The execution of the bass is fast and agile. It gives a good punch, but the air movement is not very large. This detracts from its credibility, realism and energy. Although the impact on the sound is clear, in order to remain, the lower range is stretched towards the mids. In this way, the lower range has adequate body and density, generating good volume throughout the range. Although this can be a danger in the transition, more pronounced in the low tuning, while in the high tuning, this effect is much more controlled. In warm tuning this effect is somewhat minimised, but maintains a characteristic warmth. Hence, of course, the name of this setting. Although the effect persists, you can live with it, and I find it quite pleasant. The technical ability of the MD4s contributes to a better transition than the same tuning with a dynamic driver and the speed of the set manages to untangle the mix.
Back to the sonority, the lower bass drums are quite rounded, smooth, with a point of projected energy, limited power, quick recovery and no aftertaste. The colour and intrinsic BA properties detract from a certain depth, viscerality, the sensation is less physical and sensitive. Clearly, bass-lovers may miss these qualities that dynamic drivers do provide. By contrast, the MD4s make up for these shortcomings with a special, descriptive roughness. The timbre is not the most accurate or pure in the sub-bass area, but the texture is remarkable. Thanks to the agility of the drivers, the bass has good layering, is well defined, does not mix and disperse frequencies easily, as well as generating planes with simplicity and has the ability to define complex passages, without mixing or blurring the rest of the sound and without losing the thread of the bass. In this respect, the level of resolution is remarkable, and clean, well-recorded electronic genres are reproduced with quite good technical class, which makes the sound more dynamic and allows the rest of the sound ranges to shine.
I would have preferred a tuning more inclined towards the sub-bass, but I think that for BA drivers it can be a more complex task, in this price range. Finally, the energy level they can withstand is high and the performance is clean at certainly high volumes. But they will never hold as much as a dynamic driver, so that’s something to keep in mind.





If the bass has a colour that detracts from its purity in the lower frequencies, in the mid-range we are on the other side of the coin. It is here that the MD4s express their most realistic and faithful level of realism and fidelity, as well as generating a vast, but well-spaced and airy body mass. I could say that the MD4s’ midrange sound is organic, very natural for coming from a BA driver. I think I have to swallow my initial thoughts about the frequency response and acknowledge that the result is very good in this midrange. In addition, the incidence of the switches, as well as the tips used, allows us to adjust the tuning to our liking. To begin with, the first half of this range is very well represented. In the warm position I like the body of the male voices and the density of the instruments. The timbre is very appropriate and that is part of that organic character, mixing an analogue point with analytical nuances. This combination creates a particular sound, while the tuning enhances the mass, bringing it closer to the listener and filling the scene. I have to admit that the sound is very big, full, intense, but never crowded or heavy. There is no darkness, no attenuation. You can even get a more neutral mid-range, which can never be blamed for a lack of homogeneity or balance, although it may seem otherwise. And I am referring to those mid-highs that I might have feared. It is true that the jump exists and the warm tuning brings the levels closer together. But I must surrender to the evidence and discover, with pleasure, that the FR does not reflect the reality as I thought it did. I thought it was going to be more intense, brighter, more uncomfortable, more uneven. However, it is much better. I can’t say that it is a totally balanced strip either, but the result is well compensated. And again I appeal to the switches and tips to adjust the result. Both halves of this stripe complement each other, they don’t fight each other, they don’t overshadow each other, they don’t overlap. Rather, everything flows in the same direction and under a premise of mutual respect and synergy. The first part offers body, mass, density and the second, exuberance, clarity, transparency, sparkle and vigour. The result is a great symbiosis ready to be enjoyed by the listener.





This mix of organic, analogue and analytical character persists in the high end. The treble may stand out more or less, depending on the selected tuning. But everything is kept in check and well placed. It may seem that the sound is more vivid, both in the mid-highs and in the highs. That’s why I use the warm tuning. But you may also want a brighter representation for some occasions. That’s what the switches are for. So it’s great to be able to activate them at will. The result is not long in coming and it is worth remembering that the character of the MD4 is never lost in these combinations. The upper zone is descriptive, with a good energy point. The notes are not completely thin, but have a subtle softness that gives them a certain thickness. The level of resolution, however, allows their representation to be precious, with a point of delicacy, well outlined, with visible and palpable edges. In this way, the trebles are well modelled, keeping their naturalness, without losing any sparkle or air. The tapering extension redesigns a new control zone, and this is another success in the tuning of the MD4s. The top end is not very high, but the technical capabilities of the drivers act to help the projection of this zone to be adequate.



Soundstage, Separation


I find the scene vast yet frontal, as if it were a wall. And it is a big, high wall, which looms overhead. There is a close presence that lifts the sound almost overhead. That’s why there is a good ethereal feeling, but also because of the excellent separation, amount of air and the analytical capacity of the ensemble. The laterality and stereo feel is also very appreciable and this is helped by the explicit positioning of details: it is very easy to locate nuances and small musical features. There is space between notes, air, a good dark background, more than enough resolution to discern where some elements end and others begin. The only thing I could miss is a greater depth: the grandeur of the sound and the proximity work against a clearer expansion on the longitudinal axis. Although, I must conclude that the generation of planes and layering of sounds is pleasing and insightful.
Needless to say, the recreation of the scene is realistic and obvious, without getting out of one’s head, but generating a good holographic feel, thanks to the remarkable layering and stratification qualities already discussed.
At the limit, micro detail exists, but without becoming critical, cold or too clinical. It is remarkable, but not superior.





BQEYZ Autumn (Normal)


I like to compare IEMS with similar profiles. But on this occasion, I found it difficult to find a similar frequency response. In the end, I have decided on a great model. This is the BQEYZ Autumn with normal filter. It is a single Dynamic Driver with a system of interchangeable magnetic filters (three), which offer a great level of detail, musicality and performance in all bands. Undoubtedly, this is a premium model on a par in design and construction, very attractive as well. Only the Hidizs’ level of accessories would be superior, although I like the Autumn’s cable better, and it can be chosen in three terminations (2.5mm BAL, 3.5mm SE, 4.4mm BAL).
From the outset, the sound is different. The different profile is instantly noticeable. The Hidizs are more sensitive and possess a greater frontality across their entire spectrum. Their close, almost overhead mids contrast with the Autumn’s more relaxed sound. You feel the deeper, more natural and realistic sub-bass of the BQEYZs, with the low end being more linear and cleaner. The MD4s’ bass is more restrained and compact, faster and more fleeting in its recovery. There is a more natural and realistic elongation in the BQEYZs, and they are able to withstand higher pressure without suffering. The mid-bass of the Hidizs, more swollen, also exalts the first part of the mids, being more dense, full-bodied, close, present and big. In this same zone, the Autumns are thinner, feel more delayed and need more power to gain physicality and find more balance with the Hidizs. The MD4s offer more immediate, undemanding performance throughout the midrange. Their sound is wider, closer and more evident. The Autumns are thinner in the first half and this is noticeable in the body of the male voices. Their mid-high tuning seems more delicate, less aggressive. While the Hidizs persist in the evidence, even in the details, being more analytical and explicit. The timbre shifts from one to the other. The warmer tuning of the MD4s is noticeable in this position, while the normal tuning of the Autumns is more neutral. Both have a great ability to extract detail, only the MD4s have a more prominent and palpable ability, while the Autumns offer an almost similar performance, but with a more forced performance: just as the bass reproduction of the Hidizs is more critical, because their drivers lack the suffering ability and dynamic driver performance of the BQEYZs, so it is with the mid-highs and highs of the Autumns. These generate a good performance, but everything seems simpler and less forced in the MD4s, which have a greater expressive facility in this phase than the Autumns. The BQEYZs also present the details, but perhaps at the cost of a more incisive sound, while the Hidizs have managed to blend smoothness and analytical ability.
There is a critical point with Hidizs: when playing bass-heavy electronic music, with very detailed mids and very defined highs, they are able to discern very well in the mids and highs. But bass tends to suffer at the limit, if you enjoy it at high volume. There is more control throughout the range in the Autumns, but you feel a sharper and more penetrating upper-midrange and early treble.
The Autumn’s soundstage is deeper and more oval, with good laterality, but it’s smoother and more vaporous. Whereas the Hidizs stand out for their wall of sound, closer presence, higher pitch and a slight point of better separation and amount of air. But at the end of the day, it’s a different staging in both IEMS: it’s like comparing a dense, wide plane (Hidizs), with a semi-oval (Autumn).





OK, I know that graphs don’t say everything about the sound. But in this case, the example is even clearer. The FR of the MD4s surprised me at first, because it was different and not very homogeneous. But once you put it on, it is neither one nor the other. The sound is much better. Except for the classic BA-ness of the low end, there is an effort to recreate bass in the best possible way, within its price range. To hardcore bass-lovers and electronic music lovers, they may still be a little coloured. But for all other music, such an effort is remarkable. In the mid-range there is no doubt, the tuning works: the speed of the drivers, the great technical capabilities, coupled with a great mix between low and high mids, generate an excellent range, close, full, wide, big, detailed, clear, transparent, quite natural and with a good timbre. All this, without losing neutrality or fidelity. The treble is no slouch and maintains the level without being critical or too bright. Hidizs has generated a good tuning with them and a drawing that unites control and sparkle, to vitalise the sound. Finally, that synergistic union of organic and analytical sound delivers a big, loud, ethereal, spacious and very well-defined scene.
The final touch is a compact presentation, with good accessories, both in quality and quantity, and an elegant, luxurious, comfortable, ergonomic design, with three pleasant and attractive colours.
As a final point, the Hidizs MD4s win when compared. At first glance, the sound may be relatively good. But when you go back to other models, you realise that they are better and you start to miss those features that you didn’t see as virtues at first. And you don’t experience that with just any model.



Sources Used During the Analysis


  • Hidizs S9 Pro.
  • Hidizs AP80 PRO-X.
  • S.M.S.L Sanskrit 10th MKII + iFi ZEN CAN.
  • HiBy R3 Pro.
  • Earmen Colibri.
  • Earmen Sparrow.
  • xDuoo Link2 BAL.
  • Tempotec V1-A + Hidizs DH80S.
  • Tempotec Sonata HD V.