Hidizs MM2 English Review


Valve Innovation




Construction and Design




  • Great low end with red valves. The result is a bass tuning with good mids and clarity.
  • 3 different tunings via screw-in rear valves. This is unusual in this price range.
  • The valves can be changed by hand, without the need for additional tools. The very long thread makes the system very secure and prevents them from falling out.
  • Level of the cable and accessories in relation to the price.
  • Low weight of the capsules.
  • Hidizs could potentially create more tuning valves, increasing the value and diversifying more tunings of the same model.




  • Somewhat large capsules.
  • Soft treble and not very extended.
  • The valve system is a bit slow to change, due to the very long screw thread.


Purchase Link




Link to the Store






Hidizs is in luck. It is proving that it is good at designing and manufacturing IEMS at competitive prices. The clearest example of this is its latest creation. The MM2 is a hybrid IEMS with a 6mm low voltage BM magnetostatic driver. The base is a 10.2mm dynamic driver that handles bass and midrange. In addition, Hidizs has designed a tuning system based on 3 valves that are screwed on the outer face of the capsule, allowing 3 different types of tuning. The capsules are made of two types of materials, the inner side is made of an environmentally friendly resin, while the outer side, made of aluminium alloy, is cut in the shape of triangles, to give a diamond shape. High-purity oxygen-free copper (OFC) and silver wire, also of high purity, have been used for the cable, stranded in 60-strand strands respectively. The result is a 4-wire coiled cable, which has 2Pin 0.78mm connectors, a pin and a 3.5mm SE straight plug. It comes with an elegant leather case custom designed just for MM2. The environmentally friendly and stain resistant Napa leather case comes with a full drop protection cover. 6 double zinc alloy buckles are used for support. This protective case is the perfect size to accommodate your Hidizs MM2. Among the accessories are two sets of silicone tips and a plate that houses the threaded valves. It is clear that Hidizs takes care of the packaging with respect for the environment in mind. We will take a closer look at all the benefits of the new Hidizs MM2 in this review.





  • Driver Type: 1 x 6mm balanced membrane magnetostatic driver and 1 x 10.2mm dual voice coil, dual cavity dynamic driver with PEK macromolecule polymer diaphragm, developed by Hidizs, version 2.0.
  • Frequency Response: 20Hz-40kHz
  • Sensitivity: 104±1dB@1kHz
  • Appearance: German eco-friendly resin body, aluminium alloy faceplate, aluminium alloy output nozzle.
  • Impedance: 18Ω@1kHz
  • Rated Power: 5mW
  • Cable: Mix of quad stranded cables (2-core high purity silver wires and 2-core OFC cables), 1.2m length.
  • Distortion Ratio:
  • Jack Connector: 3.5mm SE gold-plated plug.
  • Capsule Connection Type: 2Pin 0.78mm with gold plated pins.
  • Weight: Approx.10g (without headphone cable).





The Hidizs MM2 comes in a long, dark box with dimensions 154x96x55mm. On its main side, a realistic photo of the capsules can be seen in the centre. In the top left corner is the brand logo, in a dark gold ink. At the bottom, from left to right, you can see the Hi-Res Audio logo, a description of the product and the model.
On the back side are the specifications, in several languages, as well as the brand’s branding, all in white on black.
In reality, all this is nothing more than a sliding cardboard wrapper. After removing it, a black plastic box can be seen, with the brand’s logo and slogan inscribed in the centre of the main face. After lifting the lid, you can see a foam rubber base, covered with black cardboard, where the capsules are placed. On the underside is another black box, with the brand’s logo and slogan in dark gold ink. Inside the box are the accessories. Finally, there is another small rectangular, flat box, which contains the guides and cards. In summary, the complete contents are as follows:


  • The two MM2 capsules.
  • 1 3.5mm SE headphone cable.
  • 1 leather carrying case.
  • 3 pairs of dark grey, narrow-channel tips, sizes SxMxL.
  • 3 pairs of dark grey, wide-channel tips, sizes SxMxL.
  • 3 pairs of adjusting valves (treble, balanced, bass).
  • 1 User’s manual.
  • 1 Warranty card.


Hidizs accessories are always of high quality, the cable follows in the footsteps of the one used for the MS2, beautifully made and very manageable. The leather case is very elegant, distinctive, well constructed and just the right size to house the IEMS and the plate containing the valves.
All in all, both the presentation and the fittings are of a very high standard.



Construction and Design


Hidizs MM2 can be chosen in two colours: black and silver.
The capsules are made of two types of materials, the inner side is made of an environmentally friendly resin, while the outer side, made of aluminium alloy, is cut in multiple triangular planes to give a diamond shape. The outlet nozzle is made of aluminium alloy and has a grid of the same material, with small holes. Its approximate total length is 5mm. It has 3 diameters, the base diameter is 6.6mm, the central diameter is 5.4mm and the outer diameter is 6mm.
On the inner side there is a small hole, right in the centre of the drivers. There is also a white top with the channel lettering on the inside.
The size of the capsules is medium to large, they have a good thickness and the shape of the outer face, as well as the valve system, make them look big. Despite this, they are extremely light. The transparent inner side allows you to see the inside, the drivers and the cables. On the side edge of the capsules HIDIZS.COM can be read in white ink. For the 2Pin connection there is a small oval plate on the surface where the holes are located.
The 2Pin connectors of the cable protrude on a smooth surface, formed by 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 MS2 sibling. 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 time, this piece is not movable and does not rotate. Finally, the top ring is again copper, in a colour 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 unintentionally.
The cable consists of high purity oxygen free copper (OFC) and high purity silver wire, stranded from 60 wires respectively. All of them form 4 coiled strands, one pair is a dark golden colour, while the other is more silvery.
Finally, the tuning system of the MM2 has to be mentioned. It is a screw-in valve. They look like screws and in their crown there is a filter/grid that allows you to change the tuning of the sound. The crown has grooves that allow it to be screwed in by hand, over the hole in the centre of the outer face. The screw-in surface is relatively long and the exchange process is not the fastest. However, it is safe and no additional tools are required to change them. Three filters are available:


  • Rose Gold – Balanced.
  • Dark Red – Bass.
  • Silver Gray – Treble.


Of course, there is a small metal plate that allows you to screw on unused filters and this can be stored neatly in the case, along with the headphones.

In my opinion, the design is excellent and innovative, as far as the tuning filters are concerned. The inner shape is classic and the outer face has a different touch because of the diamond cuts. The capsules are a bit fat for my taste, but you have to take into account the screw-in filter system to understand this increase in thickness. It is not a critical point at all. The resin mix of the inner body and the metal outer face is justified by the same principle, a metal thread is more durable. The valve system is not the fastest, but it is safe and performs its function adequately. The cable is outstanding for the price.
The only downside is that the aesthetics of the capsules are somewhat compromised by the thickness/size of the capsules, in combination with the diamond cuts on the outer face. And the feel of the outer face, despite the specification that it is made of aluminium alloy, is that it looks like plastic. Perhaps this is due to the surface treatment and the light weight of the capsule.



Adjustment and Ergonomics


Despite what I said about the thickness, the shape is ergonomic and fits like a glove to my morphology. The fit is superficial, although it could be deeper, but the diameter of the mouthpieces may prevent it. The capsules sit very well in my ears, fitting in a durable way, which offers no possibility of rotation. With good tips, a remarkable level of passive isolation is achieved. The weight is very low and the occlusive sensation of the set is remarkable and with a high fixation. The size and thickness do not reduce the fit or the ergonomics of the set.







Three valves, three different tunings. Although the reference and treble tunings are similar, the bass tuning is my favourite. The profile varies from a u-v of the reference and treble filters, with more emphasis on the high-mids, to a balanced v with the bass filter. For the rose gold and silver filters, the accent on the sub-bass is not so high to be considered a more pure u. Likewise, the clipping in the first treble and its more limited extension also contributes to the profile’s departure from a canonical u.
The emancipation of the mid-highs is superior with these filters, something that polarises the sound towards a leaner mid-bass, offering a character that emphasises details and edges, rather than boosting the body of the notes. There is a benefit to female vocals and those instruments that feel supported by an enhanced pinna gain. In this way, a certain sonic imbalance is noticeable, something that is extreme with the silver filter. It is not a completely sharp sound, because there is a slight clipping at the beginning. The aim is to gain clarity, even though it is not technically an analytical sound, which allows one to take advantage of such an appropriate level of transparency. The result is a somewhat forced tuning in that sense. It may work for a while, with some genres. But for some amateurs, it can be excessive and fatigue easily.
With the reference filter, the bass is gently boosted and the emphasis of the high-mids is subtly limited. I would have preferred less treble control clipping and a smoother, more sustained pinna gain. With this rose-gold filter, the sound becomes more tolerable and less shrill. Warm sources may even help. But the low-mids are still thin and the nuances/details are still boosted over the fundamental part of the notes. I insist that there are IEMS that even have a higher pitch in this respect. But these have a higher technical level. The Hidizs MS2s themselves have a much wiser tuning in the mid-high range, although their lower range is also lighter. There is a balance in them that has been lost here, with the reference and treble valves.
Although, with this reference filter, the basses work better and we get closer to the u-tuning, the lightness of the first half of the middle tunes the sound, making it less dense, with a tendency towards hollowness and a distancing of the male voices. Texture is lost in this part and, not only that, but also prominence in this more fundamental part. The timbre is not bad with these filters, but they do feel inferior because of the final sonority they provide, losing naturalness.
In short, the treble filter is not well named, because the treble, purely speaking, remains almost the same as in the reference filter. What is tuned are the bass and the mid-high frequencies. It is clear that this affects the perception of the treble, gaining more presence. But what is emphasised is the part just before the treble. It is a specialised and particular tuning, for experienced amateurs who want to extend their collection.
The reference filter looks more like the treble filter. I would have liked this filter to have the same high-mids as the low-frequency filter. I think the tuning would have been more accurate, for those who find the lows of the red filter too much. Maybe a new filter like this can be created? I’m sure it could. Potentially, the MM2 could allow this and other tunings. I would like Hidizs to investigate this possibility and develop more tuning valves, with the intention of improving and prolonging the life of this new model.
And now I will focus on that red bass filter. The tuning obtained with these valves is a balanced v-tuning. Although the lows are big, the mid-highs have a similar gain to them. In this tuning, this upper area is clearly softer than with the reference and treble filters. But it is true that the feeling is more bass-heavy. The soft treble of the set does not contribute to a brighter or more neutral sound either.
After this long introduction, I will focus on describing the sound of the MM2s with the bass valves.





I must admit: I love the bass of the MM2s with the red valves! After this exalted and not very neutral statement, I have to argue my opinion. It is true that the bass response is emphasised in the centre and extends to both sides. This extension is clear towards the mids and somewhat less towards the sub-bass. It is not a bass leaning towards the LFOs, but there is a great depth and remarkable representation of that audible end. This results in a great 3D representation in the low end, with very good layering and recreation of planes.
Bass is punchy, with excellent physical representation and punch. A certain level of controlled violence can be appreciated in this lower range. The perception of air movement is high. The low end has a very particular sense of depth/smoothness/texture. It is true that the tuning is mid-bass oriented, but the bass never lacks depth and always comes across as very full. The sense of flooding comes and goes. There is a remarkable speed, decay and recollection. Initially, I thought this curve was going to provide a more rubbery, elastic and slower bass. But, in fact, the low end is quite dynamic. It’s not the tightest and most concise bass on the market, but with a level of physicality and punch like this, you can’t ask for more at this price. Even the technical parameters of definition and level of resolution are high, and the overall sonority of the area is far from a simple, round bass. On the contrary, the complexity of the range allows for dense bass, high loads and difficult representations. The MM2s are capable of realistically drawing bass that is difficult to reproduce, without falling into an easy way, showing themselves to be skilful and resolute in this type of situation.
Because the sense of openness is very high, there is room for a lot of bass and no congestion. On the contrary, the characteristics of the lower range enhance the scene.
The timbre of this area is characterised by a natural tendency. The texture and descriptive level may vary with the sources, but it has a good relationship between smoothness, thickness and roughness. Although it is never abrupt, the technical characteristics of the ensemble allow the development of medium/fine-grained surfaces, a representation that helps to make the bass more pleasant and attractive, if possible.





With a frequency response that is so rounded in the low end, it is easy for heat to escape into the midrange. But the remarkable agility of the bass prevents the bleed from being detrimental. With the bass filter, the first half of the midrange is full-bodied, but juicy. There is a clear density and presence, but a sense of muddiness is non-existent. There is no discernible mis-timbre in this section. The male voices benefit from this. And, although these are not IEMS with mids present, these voices are not simply smooth, thin or round. The bass filter rescues these vocals from the hollowness and lightness that is seen with the other valves. This is much appreciated and shows that the bass filter is not just for that, but that the mids achieve a balance from which the whole sound benefits. It is true that the drums, bass and other instruments in the segment feel more emphasised than those male voices, but the final result is quite pleasant and musical, as a good level of texture and descriptive power can be appreciated, moving away from a simple, distant, lean and thin representation.
On the other hand, it is also worth noting that the sound is sufficiently airy and spacious, so that density does not take over the scene, allowing for a good sense of separation and transparency. In this sense, the appreciation of dynamics and clarity brings cleanness and openness to the mids, avoiding congestion, pressure and lack of definition. The character is fun, lively and moderately lively. The agility of the drivers contributes to this beneficial perception. Although, at times, it is possible to observe an impression of a wall of sound, due to the power of the low end and upper mids.
The greater emphasis on the upper-mids helps to bring female voices more closely into view. But on this occasion, it is not such an obvious emancipation, as the emphasis is shifted to a higher zone. In this way, there is not such a great difference between low and high voices, it is a somewhat more selective position, but within an appropriate balance.
In this sense, although the lows are more stellar than the mid-highs, it is the balance between the two peaks of the V that creates the sensation of a wall of sound. This balance is also apparent between details, nuances and fundamental notes. This harmony is more noticeable and adequate than with the rest of the filters, resulting in a more natural, moderate, pleasant and euphonic reproduction, where everything flows with a more adequate and less forced realism, in spite of this more generalised bass character.





The treble of all three valves has a similar tuning. For all practical purposes, the frequency response is practically the same. It is only noticeable that, with the bass filter, the treble is subtly softer. A priori, I don’t have the feeling that the magneto-static driver is a superior improvement in the treble. First of all, because the tuning is similar in the initial part compared to the previous MS2s. Then, even the MM2s have less extension and less air than those MS2s, which use a BA driver for the high frequencies. It is a bit difficult to understand using a specialist driver for treble and ultra-high frequencies and tuning it in such a controlled and nuanced way. It is true that, perhaps, its sonic properties enrich the sound, being fast, crisp, smooth, detailed and capable of layering the high notes (as described on the website itself). But I miss more treble extension, more emphasis and more air presence in the MM2s. What is true is that the high notes are fine, well shaped and agile.
The first treble has a quick and slightly sparkling response, with limited projection and low persistence. The control cut should be lighter and the treble should breathe beyond the first stroke. Is this insistence on control due to a way of naturalising the timbre of the upper range? I don’t find the sonority abnormal, but it is true that the timbre in this zone is different from a dynamic driver or a BA driver. On a DD, I find the treble of the MM2s to be more agile and have more sparkle (talking about DDs of similar price). It is also true that the transients are faster. On a BA, the timbre is less metallic/analytical, but they also have a particular sound. It seems to be about finding superior technical characteristics for the treble, while maintaining a natural timbre. However, it seems to have been more important here to offer a very controlled, smooth and more common treble response than to explore a more extended and linear response. In this way, the result is similar to a classic dynamic driver curve, but with different technical and sonic properties, including a generalised excessive softness throughout the high range. Perhaps the use of a real treble valve would be necessary to resuscitate the area a little.



Soundstage, Separation


The soundstage is another of this model’s strengths. There is a clear sense of openness, height, width and depth, but without it being an out-of-head, fully volatile or ethereal sound. The sound has a good ability to breathe, within a well-separated and uncongested environment. The depth of the bass and its expansion provide distance, the mids are distributed with a definite fluidity to both sides and the headroom is clearly perceptible. Thus, the three-dimensional recreation is quite good, even though the sound is not completely immersive, but realistic. The separation in the ambience is palpable and the three ranges are distributed without clumping in the scene, which facilitates a quite logical and natural positioning of the elements. The separation between notes is obvious and the background is easy to see, because there is a good definition and resolution capacity that allows it. The level of detail is not micro, because there are small nuances in the mids that tend to be masked. It is not an analytical sound. Rather, it is a smooth sound, with good resolution, that has good technicalities, but not enough for overly critical listening. To my mind, a sense of cleanliness, harmony and smoothness predominates, offering a pleasant, musical feel, without reaching the more technical level of the MS2s.





NF Audio NM2


The NF Audio NM2s, in relation to the Hidizs MM2s with the reference valve, have some improvements that could possibly be easily solved with an additional valve. The NM2s have a little more sub-bass, fuller mid-bass, less emphasised mid-highs, a little more first treble and more air. The result is a more balanced intonation, closer and fuller male vocals, and a more appropriate brightness, not to mention that they are technically more analytical. The MM2s have a subtle comparative veil, lacking the sparkle of the NF Audio, so they appear softer and less vivid. The NM2s seem more agile and dynamic. Where the contest is closer is in the low end. There is some initial advantage to the NM2s because of the slightly more sub-bass and a bit more speed, which gives a more concise bass with less decay. They also have a bit more texture and roughness. However, their bass is slightly coloured, comparatively speaking. Whereas the comparative darkness of the MM2s favours a deeper, more sensory bass. The timbre is favoured in this respect and the Hidizs have a plus point here. It is not easy to live up to the bass of the NF Audio, or even above it.
In the midrange, the better balance of the NF Audio presents vocals more favourably, while the MM2s focus more on detail, leaving them a little more delayed and a little leaner. The slightly higher brightness of the NM2s also improves the perception of nuance, including timbre. Although the NF Audio is more analytical, the level of micro detail is not much higher and is equal in some respects.
Separation seems more palpable in the NM2s, but the soundstage is more open and higher in the Hidizs.
In terms of sensitivity, the NF Audio are very easy to move, weigh very little and are quite comfortable and ergonomic.
But this is where the NM2s end, while the Hidizs MM2s continue. I think the cable and accessories are better on the Hidizs, even if they are cheaper. And, of course, they have a tuning system that allows for a major change in sound, making the MM2s more different from the NM2s. In this there is no doubt, what Hidizs is proposing is a step forward in a very affordable price range. With even greater potential, if Hidizs decides to design more valves. This differentiating element is a clear victory over the NF Audio NM2 and many other conventional single-tuned IEMS.





It is clear that Hidizs innovates and dares to try new things. With this new model they have introduced a couple of key elements: the new 6mm balanced membrane magnetostatic driver and a tuning system based on screw-in rear valves. The brand could have been more cautious and tested each element separately, but they decided to make one model with both new features. The result is not entirely positive, but very encouraging. The filters work, but the tunings can be a bit extreme. For bass lovers, the red valve will be definitive in the system. While the other two have a bolder profile, where the high-mids are too prominent. There is a gap in the middle, which could be explored with other new valves. As for the driver used for the high end, I think it is under-utilised. The treble presence is too soft. Although one can easily get used to a nuanced treble tuning, especially if the low filter is used, it is more difficult to justify with the other two valves. In my opinion, the tuning achieved with the reference and «treble» valves should be rethought, in a way that the existing energy in the high-mids and treble should be distributed: what is left over in one should be added to the other, achieving a balance that should be more harmonious, balanced and natural. However, the reference filter is not strange, as similar tunings exist, but the technical competence and the smaller treble extension work against it.
As a final conclusion, the Hidizs MM2s are a bet on the future, an idea that has great potential and can be further improved by adding more tuning valves or revising the magnetostatic driver to tighten up the treble. While at present, the MM2s could become a reference model for bass-lovers looking for a light and smooth treble tuning, with a great stage, remarkable separation, pleasant mids, relatively close, without giving up a good level of resolution, clarity and transparency. Without a doubt, they are very high on my list of recommendations for those looking for the best bass in this price range.



Sources Used During the Analysis


  • Hidizs S9 Pro.
  • Hidizs AP80 PRO-X.
  • Hidizs DH80S.
  • Earmen Colibri.
  • xDuoo Link2 BAL.
  • Burson Audio Playmate.
  • TRI TK-2.