New Head-Fier
Hidizs mm2 mermaid Properly tuned proper magnetostatic hybrid
Pros: Boosted but well-controlled bass
recessed yet natural mids
detailed, sibilance free treble
Cons: although the treble is boosted it doesn't highlight the full spectrum of the treble region. a more smooth and even treble would have been better.
When a manufacturer uses a different driver type in their products this usually turns some heads. I mean when a product segment has a relatively steady phase any difference in a product tends to peak the interest of people.

This is something that many manufacturers knows and takes some advantage of. We’ve seen many brands take an innovative approach to the IEM’s with different drivers like planar magnetic drivers, electret or magnetostatic drivers Est's you name it.

When things come to magnetostatic drivers Shuoer started the trend with their Tape and singer back in 2020 and kz followed the trend.

A magnetostatic driver is a relatively exotic driver. It's basically a dynamic driver but cannot produce low frequencies. It's detail retrieval capabilities makes it a good choice for any IEM that is under 120 or so bucks. It's definitely a better option than any BA driver that most of the budget options like kz uses. Higher end options like Knowles has a similar level of detail but sometimes lack the natural timbre that they have.

Well using this depends on how good you can tune them. In this case, shuoer and kz kinda failed. According to other reviews, tape was too shouty, singer was too sharp (haven’t tried it) and kz failed big time; both ZEX and NRA had great detail capabilities especially with the strings and vocals but damn they were bloated as hell, well not too much but it killed the details.

Why am I mentioning these? Well because I want to emphasize on how important it is to a manufacturer to understand the components that they are using.

Hidizs mm mermaid is a good example for this case. Why? It’s hybrid model that uses a magnetostatic driver. And it's tuned to be bassy. It has a lot of bass. But it's extremely well controlled.

It's V shaped. So it's a given to lose some details in the mids. This would be the case with any dynamic driver based model but thanks to magnetostatic driver in this model there’s not much of lose of detail in the mids. Yes they DO sound distant that's the case with V shaped tuning. But in the end, it retains the little nuances in the mids.

Bass is noticeable. Like I said it has a lot of it. It kinda rolls of below 50 hz. This does affect the Soundstage; it focuses everything in front of your head instead of a 360-degree bubble effect. It’s not bloated but this amount of bass will eventually mask some of the little details in the treble region.

Treble is another area where gets some extra attention. It is elevated but it doesn’t shows any sibilance or sharpness. I especially enjoyed the high hats and percussions. They definitely sound great with the mm2. But it suffers the adverse effects of boosted bass; although its fun it doesn't highlight all of the details in this area.

Also, mm2 has some filters for tuning options. They control the amount of air the dynamic driver gets. It increases or decreases the amount of bass. Don’t expect any changes in the mids with them. Depending on the filter you either get extra bass or treble. I don’t think that they are gimmicks but I so think that it's not a mandatory thing to have. I personally don’t think you need them because in the end you get the same flavor with minor changes. If there was a way to change the tuning between a warm-neutral and this V shaped tuning that would have been a better idea. I think a switch would be a better option for this purpose.


Accessories and presentation wise this is a very good product. Although I think KBEAR and BGVP has better eartips mm2 doesn’t lack that much. It is a good option for anyone who wants a v shaped IEM that has good quality mids. And also people who might want to try a magnetostatic hybrid would definitely be happy with this IEM. It's the best option right now. I would be happier if there was a more balanced alternative for this driver combination. This setup has good potential but it cannot bring its full potential with this engaging fun tuning. As a product, Moondrop Aria holds the top spot for the warm to neutral segment. Having a magnetostatic driver alternative in this segment might be a good idea. After trying a neutral-bright IEM like TKZK wave I realized that there's not many options for bright-neutral alternatives either. offering extra alternatives in these segments could be a good move depending on the tuning and detail retrieval. MM2 does have the necessary detail potential so its up to the Hidizs.
let's wait and see what the future holds.


500+ Head-Fier
Yet Another Budget Contender
Pros: Excellent stock cable
– Comfortable
– Very good staging for the price
– Good separation
– Engaging bass response
– Tuning filters allow different levels of bass/treble.
Cons: Rose-gold accents on the Hidizs MM2 cable might be a turn off
– Lower-midrange recession
– Upper-midrange sounds strained on treble and neutral filters
– Steep treble roll-off post 7kHz.
– Needs to be priced lower to be competitive

Hidizs’s latest IEM release are the MM2 and they feature a hybrid setup with 10.2mm dynamic driver for bass and mids + 6mm magnetostatic driver for the treble. This combo is often seen on more budget-tier IEMs so Hidizs need to differentiate their product somehow. Turns out, they opted for a tuning system based on removable screws on the back of the IEMs.

Let’s see if the tuning system alone is enough to make the Hidizs Mermaid MM2 an worthy contender in the <USD $100 IEMs space.

This review was originally published on Audioreviews.
Note: the ratings given will be subjective to the price tier. Hidizs sent the MM2 for evaluation.
Sources used: Lotoo PAW 6000, Sony NW-A55
Price, while reviewed: $80. Can be bought from Hidizs’ Official Website.


Both the stock cable and the carrying case deserve a mention here, since they are some of the best you can find in the packaging of IEMs under USD $100. The stock cable is supple, doesn’t tangle easily, and looks great.


The carrying case is somewhat over-engineered yet maintains a muted outlook. Rather unexpected for a pair of budget IEMs.



Build is very good with the metal faceplate seamlessly blending with the resin shell.


The filter mechanism works by adjusting the size of the back-vent, which in turns control bass quantity. There are three different filters with varying degree of bass, though I preferred the Reference filter the most.


I should note that I prefer the rear-mounted filter system as opposed to nozzle or tip mounted ones since they are more cumbersome to swap. Also it’s need stating that the passive noise isolation is below average, as the rear-vents allow noise inside. No driver-flex was noticed which is a plus.



The general sound signature of the MM2 can be described as variations of “V-shaped” tuning with varying degrees of bass and lower-treble depending upon the choice of rear-filter.


I think the bass response is the star of the show here with punchy mid-bass and good amount of rumble in the sub-bass region. The slam is also above-average so these drivers are moving good amount of air.

The issue arises in the lower-mids region where, with the stock and bass filter mids sound too recessed, resulting in distant male vocals, snare hits etc. The aggressive pinna gain around 2.5kHz compounds this further with high-pitched or soaring vocals sounding strained, as can be heard on Alexisonfire’s This Could Be Anywhere in the World. The male vocals do gain a bit of thickness with the bass filter but then again the large amount of mid-bass drowns out the subtle articulations of voice, resulting in a lack of resolution.

Treble peaks around 4kHz and then goes for a steep decline from 7kHz onward. This robs off the airiness of cymbals and hi-hats, resulting in a muted presentation devoid of shimmer and resonances. The magnetostatic driver is supposedly aiding the treble response and whereas some magnetostatic timbre can be heard, the sheer extension is lacking. Treble overall is not bad, it is just unremarkable.

What is remarkable though is the staging performance of the Hidizs MM2. Stage is wide, with instruments often being placed outside your ears in binaural tracks, e.g. Amber Rubarth’s Strive. Stage depth also seems above-average though that is mostly attributable to the lower-mids recession. Imaging was above-average though lacked the precision of some of their peers. Instrument separation is above average but is often let down by the overshadowing bass.

I wouldn’t call the timbre plasticky myself but it definitely lacks some of the richness one would expect from a natural-sounding setup.


vs Dunu Titan S

Dunu’s budget model of the refreshed Titan series have 11mm dynamic drivers with LCP diaphragm. Dunu went for a more neutral-bright tuning with the Titan S and the driver is also faster than the MM2 during transients. Due to the upper-mid and treble focus, the bass on the Titan S doesn’t have as much authority as the MM2 bass.

One area where the Titan S surpasses the MM2 is sheer resolution, with the Titan S being more revealing of mastering flaws and also having better imaging. Staging is not as wide and tall as the MM2, however, neither is the macrodynamic punch as evident.

Given the similar price, the Titan S offer great value for those who are after a neutral-ish pair of IEMs. The Hidizs MM2 will cater more to those who prefer a mainstream or V-shaped tuning.



The IEM market is the most ruthless in the under USD $100 segment as new models pop up almost daily. Hidizs MM2 stand out with great accessories and a filter-system that is quite unique, while offering various levels of bass.

Unfortunately, the mids and treble frequencies are somewhat off in terms of tuning and that mars the experience. The treble roll-off hurts the sense of resolution the most, something one would expect from IEMs at this range.

I do think the Hidizs MM2 would offer better value had they been priced somewhat lower. The accessories are quality however, so maybe you are paying the extra for those goodies.


Otto Motor

Headphoneus Supremus
Hidizs MM2 Review
Pros: Great staging, resolution, and separation in its class; tuning options with screw-on filters; great cable.
Cons: Timbre not the most organic; large shells; rose gold not for everyone.
Since the previous reviewers have already covered the Physicals, I am focusing on sound.

You find the whole story at

Equipment used: MacBook Air | Earstudio HUD 100 (low gain) with AudioQuest JitterBug FMJ | stock bass filters | stock wide-bores.

Since Hidizs give you the option to perform your own tuning with the included screw-in filters, I started tinkering with them…and finally decided on the bass vents as the created the “most substantial” sound experience for me with a great vocals reproduction.

In the big picture, the Hidizs MM2 is all in one: a neutral sounding iem (normal filters), a warm one (bass filters), and a screamer (treble filters ).



Green is my colour. Nor piercing upper midrange, no shoutiness.

In my favourite “bass” configuration, the MM2 deliver a “fun” signature with some surprisingly good sonic characteristics.

Bassy filters means serious bass, without being too serious. Focus is on sub-bass. It digs deep, very deep – and with some energy. Mid bass slam has still good impact. This makes the low end a bit blunt and less tight than I want in some tracks. I don’t think the bass is overdone, though. All in good doses. It’s fun tuning after all.

The transition to the midrange works rather well. I would not call it bleed but the bass re-inforces the vocals in the lower midrange department quite efficiently. Although recessed, female and male voices are not lean or thin but have some nice richness and creaminess. They are not your stale black coffee but more a mocha latte with 2% milk. Notes are surprisingly well rounded. The MM2 beats a notorious weakness of budget iems in this department. And, although there is enough energy in the vocals, there is no shoutiness.

Treble is well resolving. Cymbals are very crisp, clear, and well carved out, but also a bit robotic, which is an artifact of this kind of driver. And since the treble sits a bit back, the cymbals are frequently covered up to some extent. I take it the magneto-static drivers are connected and working (as opposed to some of the competition’s).

Stage is no the widest but has good height and decent depth (with the bassy filters). Resolution, separation, and layering are astonishingly good. But…the timbre…is somewhat plasticky and could be more organic. Once I got used to it is as fine. That’s the biggest concern I have about this earphone – and I’d take $20 off for that.

Concluding Remarks

So why not tune yourself? By screwing in tuning filters you also screw the noisy YouTubers…that bad pun may be allowed. Hidizs have done a decent job with the MM2 and the tuning filters, which can be helpful particularly for newbies who want to learn different sonic signatures. Nevertheless, the MM2 could be $20 cheaper imo. But, maybe Hidizs let you tune your own price, too…see included coupons.

Until next time…keep on listening!

Jürgen Kraus signature


The Hidizs MME was provided unsolicited by Hidizs and I thank them for that.

Get the MME from
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500+ Head-Fier
Hidizs MM2 Review Fun and versatile
Pros: -Not difficult to drive

-Bass is deep and punchy

-Good soundstage

-Decent separation

-Tuning Filters that work

-Fun tuning
Cons: -Odd treble at times (balanced/treble filters)

-Treble rolls off too early

-Odd look on the ear (to me)

-Using the bass filter = just too much
I had a great time reviewing the Hidizs Mermaid MM2. You can find the review in its entirety at:

Hidizs Mermaid MM2
The Hidizs Mermaid MM2 ($80-89) is Hidizs Audio's latest in ear monitor. Lately Hidizs has created some very nice iems, particularly in the budget sector. In my possession is also the Hidizs MS2 which I do regard as one of my top 10 iems under $100. Hidizs has always sought out to manufacture well-built audio gear with a distinct look as well as sound.

Can the MM2 best it's older sibling to take the helm at under $100 range within the family or is it simply another iem in a clogged market? It seems Hidizs went back to the drawing board to come up with a new design to tempt the consumer. I am a sucker for an innovative new design and I've come to really appreciate Hidizs. Granted there is nothing new here in the grand oceans sized market of iems. However, these tuning filters design and effectiveness is rather unique. Let's see how Hidizs did with the MM2 and compare it to some heavy budget hitters.

Gear used

-Shanling Ua2
-IFi Go Blu



For a set priced at $80, Hidizs put together a nice package. You receive 6 pairs of tips; #3 wide bore and #3 with a more narrow bore. All of the tips are actually usable as they are more firm, as both styles included aren't just cheap, flimsy throwaways.

Also included is a 2 pin- 4 core OFC copper cable, much like the cable handed out with the Hidizs MS2. The cable is light and easy to manage with a soft and pliable feel to it. It terminates with a 3.5 TRS single ended jack. It really is a nice cable considering the price and what we've come to expect from budget tier iems.

One thing which surprised me was the case. It is a very nice and even premium looking faux leather case. Really, I did not expect a case which felt so nice in hand. I have so many cases and rarely actually use them but this case prompts me to use it for...something. Who knows I may actually put some iems in this one. Eh, or not.

Last but not least is the small rectangle aluminum slab which is home to the screw on ventilation filters. I recommend utilizing this little slab so to never lose the filters. This is similar to multiple other little filter holders, as you can see pictured below. Within that slab you will find the "Bass", "Reference", and "Treble" with female threaded holes to each corresponding filter.



The Hidizs MM2 employs a dual cavity/dual voice coil 10.2 mm Dynamic Driver which Hidizs calls a "PEK Macromolecule Polymer" Diaphragm. From what I have read, the Dynamic Driver covers the lows and mids. To control the treble area is a 6 mm Magneto-static Driver. A unique hybrid driver setup which doesn't disappoint.

The look of the MM2 is unique and also... kind of odd in my opinion. They aren't ugly at all but maybe not my jam. This is obviously an entirely subjective observation. They just aren't something I would "Rock" daily. I'm sure some may really like the look of these but the tuning filters which stick out and look... somewhat Blingy to me. Perhaps it is the silver color which adds to the boujie look. For me the MM2 are comfortable and seal very well. Obviously, this may not be the case for everyone.

Built well enough with a sturdy frame, the MM2 don't feel too cheap to the touch. They have a transparent resin housing with what appears to be an aluminum faceplate. The MM2's in my possession are a silver color while Hidizs also offers a Black MM2 as well. They are very lightweight, easy for wearing and without any jagged points of contact to annoy over time. Hidizs always has great build quality and the MM2 carries on this trend.

Atop the Faceplate you will find a screw type tuning filter with a rather long screw which sticks out quite a bit. Of course, Hidizs had to build them in this way so that a person like myself can get a grip on the filter head to screw in and out. Nowhere near as easy and quick as something like the Bqeyz Autumn but still easy enough to install nonetheless. Righty-tighty, lefty-loosey.

As far as the build is concerned, I'm sure this look will appeal to many. It took a while for me to come to grips with the blingy appearance but after some time I guess… it's not so bad. In fact they may actually grow on me.


Sound Summary

I should start by saying that I didn't hear any sonic benefit from burning in the MM2. I stopped at 50 hours without change. Good out of the box.

I would categorize the MM2 as V-shaped to U-shaped. However, the midrange isn't crazy recessed like the majority of V-shaped iems flooding the market nowadays. The mids sound in good balance with the rest of the staging. The sound is like a mix of natural and colored. Warm in the lower region while cooler in the mid tones. I don't hate it at all, especially with certain genres. There is nice clarity throughout with these drivers which is becoming a staple of the Mermaid line.

The MM2 has a fun signature as there is nothing dull about this set. The bass hits great with any filter and much more so with the bass filter. The lower midrange is full and rich on all filters while the upper midrange has more emphasis. The treble drops off fast after the mid treble area but doesn't sound terrible to me. Just missing a bit of that energy and sparkle up top.

Each tuning filter will alter the sound to the relative naming scheme of the filters. Most tuning filters seem more like gimmicks which only subtly alter the tonality. I have seen this time after time. In fact one of the comparisons later in the review, the Fiio FD3 also has tuning filters which hardly have the effect that the MM2 filters have. The MM2 is constructed in such a way, that each filter does exactly what their name implies. To a degree. Obviously nobody should purchse this set thinking they are getting three iems in one. The change is really just shifts in the tonality, but they do actually have a nice affect.

"The bass digs deeper with excellent speed, a tight response, and is punchier. The mids are smooth, detailed, and have a more U-shaped character. Vocals are sweet and instruments sound natural.
Large soundstage, outstanding imaging capabilities, excellent layering throughout, with great presence - MM2, a pair of IEMs you’ll never regret having".

Hidiz Promotional


I used the included cable for most of my listening. However, I found that using a balanced cable seemed to help with this set. It aided the playback by providing more power using balanced sources as the MM2 does scale to an extent in my opinion. To be honest once I switched to the Tripowin C8 SPC balanced cable, I didn't go back.

Overall, these are easy to drive. I had no problem driving them from the lower powered Zooaux Dongle Dac. I would say that the bass wasn't as quick using this. A bit slower in my opinion. Not bad though. The MM2 have an 18-ohm impedance and a sensitivity of roughly 104 db per their website. Just as the Hidizs website states... these are pretty easy to drive.

However, from a Dongle Dac such as the Shanling Ua2, the MM2 seemed to find itself a bit better in the bass department. Then, moving up to the Ibasso Dx240 DAP with a balanced cable I found the MM2 does benefit a bit with more power. The bass became quicker and tighter and played better with the upper areas of the mix. I noticed a bit more openness and dynamics. Please note, the MM2 are very dynamic without the added power as well.

The MM2 don't need big power. A desktop setup is not a requirement for better fidelity. Simply add a Dongle Dac or a Dap and you'll be good to go.

(In the next section I chose the Reference Filter as I think it gives the best balance of all three filters.)


To me, the low end is one of the main characters to the MM2 story. I'll tell you what...I dig the pronounced low end here! I found clean edges to some pretty heavy bass drops without them impeding on the rest of the mix. "Big Energy" by Latto is very representative of this. In that very toe tapping song (be aware it's dirty) there is enough commotion going on in each area of the frequency. I feel the MM2 handles everything well, with clarity and with a decent slam while not suffocating the mix. I hear great energy. Keep in mind the bass is on the slower side but still does well to not muddy things up. I do hear some texture here and clean edges.

There is more volume to the mid-bass than the sub-bass but from what I hear the difference is minimal. That said, the sub-bass is still a big part of the MM2's appeal. There is evident haptic buzz vibrating my ears. People who enjoy Hip-Hop or EDM will likely enjoy the MM2 a lot. Rock and Metal sound fantastic on the MM2 as well. In fact rock music seems particularly at home with the MM2.

The low end of the MM2 is not too overbearing even with the thump which comes from this set. This pair falls short of bass head with the reference filters. I feel Hidizs added just enough weight to the low end to not infringe on the rest of the mix. The upper bass does bleed ever so slightly into the lower mids. Though that bleed over is barely noticeable and actually adds some meat to the lower mids.

With the bass filter attached the bleed further interrupts in my opinion. We get a bit of bloom and boom with this set-up. I don't like it as much. I'm sure some reading this will enjoy the bass filter just fine. I'll stick with the reference filter.

The bass hits hard with a vibrant kick from drums as well as synth bass, booming bass drops and bass guitars etc. There is some coloration to the low end, yet done in a way so to not sound too unnatural while still giving that thump. The bass is quicker than it is slow with added power (using Dx240) and slightly warm of neutral. I can attest that a bit more power does help here.

The lower parts of the frequency are a joy for me. However, some may find the bass to be too much on the MM2. Not everyone enjoys an expressive bass as I do and so this may be a problem for some.


The lower midrange is a tinge more forward than most. Nothing sounds out of place or too distant as I don't think there is any drastic recession. Granted, the low-mids to mid-mids is where you will find the greatest recession on the MM2. Male vocals cut through nice with clean edges. Nothing grainy from what I hear.

Male vocals come across as full and articulate. Though at times I do hear a very slight bit of congestion. Mostly when there is a more congested track while using a lower powered source. It's nothing terrible but the MM2 can sound a wee bit too mushed together in a perfect storm. This is a rare issue though. Still, the male vocals have good weight and sound a tiny bit colored. This coloration in my opinion only adds to the whole presentation.

When male vocals are more singled out, they sound great. There is a grain free edge to voices in this area. There is almost a plump intensity without coming across too intense, if that makes sense. I don't hear any great warmth mudding up this area from the bigger bass either.

Acting as a counterbalance to the low end is the steeper rise in Pinna Gain, quickly rising into the upper mids. I find it necessary for a good balance across the spectrum. I don't hear any shout or pierce at all, unless I really crank the volume on a track which is more prone to shoutiness. At least that is how I hear it. Somehow Hidizs struck a good enough balance as a whole.

Female vocals sound nice enough. Nothing veiled to me. Maybe a hair thin in comparison to male vocals. Nothing sounding odd though. Slightly more forward is the female vocals over their male counterparts. I hear a sweetness to females at best. What I don't hear is that emotional pull which some female vocals can Induce. They are clear and pleasing but settle at that. I would not call them dull.

Instruments also sound well resolving and for the most part the timbre sounds fine. Tonality is somewhere near neutral to cooler than neutral in this area using something like the Ibasso Dx240.

All in all, the midrange is fine, with some decent to good details in its replay. On louder volumes and in some tracks, you can hear the beginnings of shout, but nothing too bad. I'm sure many will enjoy the vocals on this budget tier iem.


The Magneto-Static Driver completely controls the treble region. The treble as a whole sound just fine, if not a little subdued.

The lower treble region does have a bite, a spiciness that adds some life to the upper frequencies. The treble as a whole is not as voluminous as the bass and midrange but nothing sounds as though anything is particularly lacking.

The treble does have a small issue for me. Not in every song do I hear this issue. The issue is the steep drop off somewhere before the upper parts of the treble, which leaves some information lost and luster-less against the rest of the frequencies. For instance, Cymbals are a slight bit clouded over in more active and congested songs. Also, around the upper-mids and through the treble is a very slight grain to the edge of notes. Not a deal breaker. Technically speaking, the treble area still picks up decent details which I suspect is the result of good resolution and clarity.

Understand that I am nit-picking. This is a $80 iem. The treble is just… fine. I just don't hear the extension all the time. Like I said before, this isn't a problem on every track, and it can go unnoticed completely. Unless of course you are a diehard treble head. In which case you would never reach for this set in the first place. This MM2 is not perfect, not that I should expect perfect, but other sets in this price point are able to do better here (treble). Hey, the MM2 are doing pretty darn good so far despite any shortcomings.



Represented very well is the soundstage, I'd even call it one of the MM2's steengths. There is apparent audible openness in the sound scape. Really, I think that Hidizs did a good job of giving the illusion of space. I hear above average width from the MM2. Keep in mind that above average is a great asset in this price point. Not every set can provide an above average soundstage. The width is appropriate to the music, and you aren't lacking anything here.

The depth and height is a hair above average. Though I think more height than depth. The stage gives ample room for instruments and voices to mesh yet remain separated at the same time.


Another strong point. The imaging of the psycho-acoustic stage is actually… done well. I didn't expect this. I hear decent to good instrument placement that is accurate. At this price anything that can induce the perception of instruments in their own place is a win for the MM2. Separation is above average for sure. There is enough space to put each element within a song in its own space with air between.

The MM2 has enough air in the mix as well as resolution to compete well against iems in its price segment. I'm not talking multi hundred-dollar level here. I'm referring to the Iems stationed at that $50-$100 range. These won't blow your mind, but they also won't muddy things up so much that they are hard to listen to. I've said it a few times; there is very good resolution and clarity here, as seen in previous iterations of the Mermaid series. This only aids the audible placement of instruments and voices. Not bad Hidizs.


Moondrop Aria ($75-80)

The Moondrop Aria is an iem which reached legend status farely quickly. The Aria has a Single Dynamic DLC Diaphragm Driver and has a Harman type tuning. This iem is in many Top #5 lists for its easy to listen to replay.

The first thing you'll notice is the Aria has a much more smoothed over presentation. More laid back than the MM2. I would say much easier for extended listening.

The stage of the Aria is slightly smaller, but they are on par with each other in placement of instruments and overall staging. The Aria has been highly regarded for its imaging, so to put the two in the same sentence says alot.

I believe the MM2 has a hair better clarity and resolution but also harder edges. The Aria is much more balanced in its replay and a bit more cohesive altogether.

The MM2 have more bass quantity as well as quality to me. That said, the MM2 is also more elevated in the upper-mids/lower-treble area creating a more V-shaped sound. Still vocals sound good on both sets but more natural on the Aria to me. Vocals seem a bit more effortless on the Aria.

Aria has better extension in the upper regions, and you simply can discern these areas better on the Aria. Couple that with the great resolution and smooth replay and you have a fantastically tuned iem. The Mermaid is no slouch though and I could easily see many taking it over the legendary Aria. I suppose it's a matter of preference. The MM2 are the more of a fun set, yet this certainly doesn't equate to better. Just different.

Hidizs Mermaid MS2 ($75-99)

The older sibling of the MM2 and one of my favorite iems in the under $100 price is the Hidizs MS2. The MM2 takes a different approach to a similar tuning. I can hear the bloodline of the Mermaid series with just different takes on it.

The Hidizs MS2 is also a Hybrid Driver but with different configurations. The MS2 sport a 10.2 mm Macromolecule Composite Diaphragm, said to be a 2nd Gen Driver. Taking care of the upper regions; a Knowles Balanced Armature Driver which gives a very open and airy sound.

It is clear when listening to these side by side that the MM2 has much more elevated bass. The low end of the MS2 may not be as exaggerated but it is much quicker and tighter. The MS2 has good punch with great clarity down low. The MM2 have more boom and heavy doses of haptic vibration.

Soundstage is actually a hair wider to me with the MS2 as there is a better balance across the spectrum with more extension up top. Of course, Hidizs wasn't going for a balanced approach with the MM2 but a fun and slight V-shaped to U-shaped sound.

All things considered; this is just another choice in preference. The MS2 is a bit colder in tonality while the MM2 has slightly more warmth due to the elevated low end. The MM2 is a more mainstream toe tapping banger, while the MS2 is a bit more refined to me. The MS2 has less of a veil but both have a more open nature. Both have great clarity. Both have great resolution. Personally, there will be times that I prefer either one of these two iems. Both catering to whatever mood or ambience I am after.

Whizzer Kylin HE01 ($80)

The next iem for comparison is the Whizzer Kylin HE01. Comprised of one Single Dynamic PU / Peek Composite Material Driver, the HE01 at one point was a sort of "hype train" iem which did not last very long. They came and they went.

Actually, the Whizzer HE01 is a very unsung and almost forgotten about iem. This is a mistake. A/Bing these two iems side by side immediately shows they are both nice sets in the price point. Also very evident is the very fun sound which these two have in common.

The HE01 wins in the bass department. Flat out. While I enjoy the MM2 for its decent thump, I can't help but enjoy the same thump in the HE01 yet with better decay and more authority. The HE01 is tighter with more slam yet with smoother edges. The MM2 is slower but still defined. Both are nice but I like the HE01 a bit better here.

Both sets present forward mids compared to other V-shaped iems. I don't dislike either in the vocal dept. Vocals come across a bit more natural on the MM2 as the HE01 has more of a knife edge to some notes in the midrange. Two different approaches.

The HE01 has a little brighter tilt with a bit more extension in the highest regions while the MM2 is a hint warmer in replay. Both sound great in the $50-100 area.

I think with the addition of the tuning filters the MM2 obviously has more options to tune them to your preference which is a win for them. Yet if you value bass that is tight yet carries authority with a replay that tilts to the cooler side of things you may pursue the HE01. Both have a certain Blingy element with the MM2 appearing more masculine and the HE01 looking almost like jewelry.

Fiio FD3 ($99 / $130)

Since it's release a year ago, the Fiio FD3 has been mostly unsung. In my opinion the FD3 is one of the better single DD's in the price point. Stylish, small and very fun are the sentiments which come to mind. The FD3 is a Single Dynamic Driver with a DLC Diaphragm. Fiio refers to it as a "Flagship Level" Driver.

I hear a slightly wider stage with the FD3 than the MM2 but the MM2 has a bit more depth. Both have wider and deeper soundstage than average however.

The overall tonality of the MM2 is a bit warmer than the Fd3. The FD3 has a bit more extension past the upper treble area and deeper sub-bass than the MM2. That said, the MM2 also has a bit more 3D of a sound.

The bass on both sets hit pretty hard with the FD3 coming out a bit tighter while the MM2 has a bit more slam in the mid-bass. Not by much at all though as neither lack at all in low end volume. The FD3 can vibrate a bit deeper in the sub-bass region. Both replay bass wonderfully for the price tier.

Male vocals are more up front on the MM2 with a hair more weight, while female vocals sound more forward in the FD3.

There is a bit more thickness and tighter edges to notes on the MM2 which helps with a very vivid replay. The FD3 are just as charming with a touch smoother sound and great tonality. As I said the FD3 has a bit more extension with a wider soundscape due to the larger back vent on the shell which lends itself to slightly thinner areas within the mix.

Don't shy away from the FD3 though. Fiio did a wonderful job on this Single DD. I think for longer listening sessions the FD3 may be the one to check out. Both of these sets are very fun however with the MM2 coming out a titch more crisp with a bit better resolution, but I am splitting hairs people. In truth I personally enjoy the FD3 as the fit suits me better.

Every set I picked to compare are some of the best in the under $100 price bracket and none of these are head and shoulders better than the other. This was simply to establish the pedigree that the MM2 can play with if the tuning suits a person.



Starting this review, I have to admit that I was not exactly a fan of this set. However as I went through the process of testing and comparing I have come to enjoy them. The MM2 are certainly not for everyone. They cater to those who are after a very fun, dynamic, and very punchy sound profile. I did not find them too fatiguing either. Still, there are certainly other iems which are easier to listen to for long periods. Like I said, not for everyone. Hidizs seems to have their arrows directed at a more youthful demographic here. Still, I have to say that the MM2 represent this style very well. Especially if you are into Rock, Hip-Hop, EDM, or even Jazz genres I'm sure you will at the very least come away respecting what Hidizs created here.

I've come to respect Hidizs and the products they produce. I feel that they always do a good job of making solidly built and premium feeling audio gear.

This review is simply a snapshot of my views on this new iem. All thoughts within are from my perspective and are my opinions. We all have different ideas about what "good" is or isn't. So now that I am nearing the end, I can attest that the Hidizs MM2 are representative of what Again, the MM2 is not my ultimate preference, but I understand what Hidizs was shooting for. Let me put it this way; If this set started showing up in multiple top 10, or even top 5 lists... wouldn't surprise me. If it turns out that this just isn't for a person...wouldn't surprise me either.

So, this concludes my review of the Hidizs MM2. For $75 you can definitely find worse V-shaped iems no matter how you feel about these. All in all, not bad at all Hidizs. Take good care everyone.

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Headphoneus Supremus
A Finicky Yet Beautiful Creature
Pros: Exciting hidden sub-bass
Nice soundstage
Hybrid dynamics
Hybrid seperation
Special technology tweeter never used in an IEM before
Reusable eco-friendly storage box
Nice complete accessories set
Perfect Tips
Unique valve tuning system
Makes friends with your MacBook Air
Introduced by a long established manufacturer
Quality design and build
Easy to drive
Big sound
Cool looks
Exciting presentation
Makes poorly recorded music sound remastered
Perfect fit and form factor
Comes with a solid aluminum faceplate in black or silver
Cons: Requirers a specific diet
Temperamental and choosy with what music it likes to play well
Valve tuning system's worth might be questionable?
Very, very unique treble tone
6mm Low-Voltage Magneto-Static Tweeter may be an acquired taste like blue cheese

Hidizs is a company with a singular purpose: To make premium HiFi music equipment available to audiophiles at affordable prices.

They started in 2009 when “pocket-fi” was just getting going. Tamson, the founder of Hidizs saw an opportunity as pretty much everything (in the portable world) was expensive and lacked quality. Being an audiophile and musician, Tamson wanted to make change! He utilized over 40 audiophiles/engineers in a new R&D laboratory pushing the boundaries of what was thought to be budget audiophile. To make a long story short, in 2014 the Hidizs AP200 DAP was a huge Kickstarter success. A staggering $280,000 was gathered by 943 backers and every single unit was shipped.

Even today they make a handful of DAPs. The AP80 Pro DAP...........both in two models, Balanced and Single Ended. As well as two non-pro editions, one stainless steel and one in aluminum alloy or copper. Prices starting at $129.00! That's right! $129.00 for an audiophile DAP!

Hidizs Mermaid MM2

6mm Low-Voltage Magneto-Static BM Driver IEMs​

  • 10.2mm Dynamic Driver 3 Tuning Valves for Different Audio Experiences
  • Eco-friendly Resin Body & Lozenge-cut Faceplate
  • Detachable 3.5mm 2pin OFC Cable Custom
  • Eco-Friendly And Stain-Resistant Napa (Synthetic) Leather Carrying Case
$79.00 Comes in SILVER or BLACK

The Mermaid MM2 we are reviewing today is second to their MS2 dual Hybrid IEM coming in at $89.00, respectively. They also make the H1 $49.00 Bluetooth Neckband IEM, and $49.00 Mermaid MS1 Rainbow IEM.

With these selected products they have supply centers in the USA, Japan and different parts of Europe, making them truly an international entity. Comprehensive global shipping is their main focus! But.......................without great sound quality, nothing is worth shipping in the first place.

Mission statement:
This is a full-review of the Hidizs Mermaid MM2 IEM. Such descriptions include aspects that are good and bad as well as possible subjective thoughts as to the IEMs performance. The IEM was provided free of charge from Kareena Tang of Linsoul. Links for purchase will be provided at end of review.


When I found out I was being sent the Hidizs Mermaid MM2 naturally I wanted to know what it was. To my surprise this particular IEM was sent out to a-whole slew of reviewers. Some had a YouTube channel but never reviewed a wired IEM before. So it was a fascinating journey which opened my eyes to the fact that a new IEM (regardless of sound) can be/offer many different things to many different people. Some were simply intrigued by the faceplate and tuning filters. Others used the Mermaid MM2 for gaming; so my typical audiophile tests may be simply another story to add to the bigger picture which is the Mermaid MM2?

Probably my most discouraging information had me believing the Mermaid MM2 was so-so. Basically a half-way attempt at what Hidizs was trying to do? I knew for sure that its design was revolutionary, but if executed correctly is maybe another story?

So regardless of technology involved, I will make some basic judgments about sound quality.

I rate IEMs on a three tier rating system:
  1. Great well-rounded IEMs
  2. Bad IEMs
  3. Finicky IEMs

I would best describe the Mermaid as finicky. That’s really it, though of course there is subjectivity too. But the Mermaid MM2 is actually very very good for what it is. It scales fact it scales really really well.

The tuning valves:

mermaid inside.jpg

I'm normally not fond of tone changing possibilities available on any IEM by any manufacture. While I find the regular tone altering ways like tip changes and DAP changes to be effective and reliable. Though the uniqueness here is that the idea of altering “air-pressure” with a single breathable-valve. Meaning manufacturers will look for and pay for people to come up with revolutionary IEM design concepts. It's making the Mermaid MM2 stand out in the food-chain. Such components of attraction have successfully been used by nature for millions of years! I will say the execution of the design works surprisingly great, even though at first you would think the valves would be a hassle. So by design the Mermaid separates herself from the thousands of IEMs in the current marketplace. Such novelty draws attention due to the curiosity it provides, paving way for the shopper to stop and look. You are looking............are you not?

The three colors of valves each go about altering a slight tone by changing air pressure release from inside the IEM cavity.

The traditional way is adding crossover (switches) electronically to change the signal. In my experience with the DUNU SA6 and qdc Anole V3 such switches did alter the signal. Though somehow the standard unaltered ways seemed best, and that goes for the Mermaid MM2 also. So after testing I reverted back to the standard valve.

Still......I’m open minded, meaning I think the ability to alter IEM frequency is the path to making the ultimate IEM, overcoming subjective tone ideas and desires, it’s just not perfected yet.

The first thing I noted was how the screw-on valves were purposely the exact right size to have the outer shell keep you from screwing them in too tight. Meaning aluminum is incredibly soft stuff, and the last thing we want is to have someone force the screw down placement affecting the threads. Here you actually lose grip in the process allowing the correct amount of actual placement without going overboard! Your fingers can’t grip the valve any longer, and that’s a good thing!

Red Valve:
Instantly recognizable, the change from the standard valve to the red bass valve added a noticeable thickness. I was going to use actual songs to try to explain the ins and outs of this experience, but later decided it wasn’t necessary. Just note that strangely the whole signature is affected, but some areas get effected more than others. And I will give them kudos for pulling this off. It really does work. Still the final outcome of the bass valve had me missing the standard valve. And the thing is these have a nice style of bass Why? And I like bass, so you would guess I would be first in line to sign-up for such an added bass Not this time!

Silver Valve:
The Mermaid MM2 has a unique treble anyway. The use of the 6mm Magneto-Static is real. It’s effects.........absolutely a thing! So to try and alter the signature again seems an exercise in futility? The thing is, I really like the regular response. It’s not perfect by any means, but for $79.00, it’s nice! It does many of the fundamentals that make an IEM good. I don’t want all that to change, don’t take that away. I mean somehow (maybe) part psychological in nature, the alternative valves seemed fake or un-natural? There was added higher-frequency emphasis and written down on paper it would seem the extra “boost” would be welcomed, but no..............not in my use. Not this time!

This IEM gets rated as Finicky. So if you have read my past couple of reviews I have a three tier rating system. While subjective metrics still apply................this particular IEM shows a character that is both fantastic and in need of catering to. Meaning it opens up to a wonderful soundstage and offers great instrument separation, though it can be slightly peaky with the wrong tracks. There can be found a slight upper-midrange and treble intensity which isn’t always noticeable all the time, but is a real phenomenon on some tracks.

Thus the same old methods/tricks of getting detail and resolution at the expense of a slightly less well-rounded IEM experience.

I am being critical but a reality is unfolding here. The Mermaid MM2 does do many things great and better than great, it in-fact does stuff spectacular! It’s just that you have to pick your music before hand.

Example 1:

Apocalypse and Chill:
44.1kHz - 24 bit

This album basically goes right ahead and explains my whole midrange-treble issue. This is not a question of using the correct IEM tips or a correct DAP, as I have previously tested all that. It almost doesn’t matter which song you choose here as pretty much all of them show what’s up. The driver is showing us it’s buzzy and treble-centric to the point of brightness at any volume.

Plane and simple really. At times there is no mystery to this stuff.

Is it a deal-breaker? Maybe not. What this has to do with is simply being technically well rounded. Some IEMs are, some are not. Some are actually bad actors as they were gifted with an uneven, incorrect and possibly incomplete frequency response. Here we simply need to choose our music replay.

Example 2:

Hans Zimmer & Junkie XL
Batman vs Superman: Dawn of Justice OST:

96 kHz - 24 bit

I mean how can this be? It’s a very thin level of adjustment that means the difference between success and failure. There is no way this playback is anywhere near bad or wrong. In fact playback is perfect. This is singularly one of my most favorite albums, I know it forward and backwards. actually I’ve never listened to it backwards but you get my drift. In fact what maybe made the Delain album bad, seems to make this album better? Huge-huge soundstage, correct instrument tone for the most part, and correct timbre. Glorious ways that the Mermaid MM2 does sub-bass. In fact I would choose this exact IEM to listen to this soundtrack everyday. Though the IEM comes in black and I would need a black pair as black is Batman’s IEM color. In fact they look like the Batmoble a little, actually they look exactly like another movies Batmoble come to think of it. How strange is that? Bat-IEMs.


And while I’m on the subject of Batman, I mean while I’ve got you here reading and all.............

Example 3:

Hans Zimmer
The Dark Knight Rises OST:
192 kHz - 24 bit

Another sold gold playback. So how can this be. These two soundtracks are played back flawlessly.......perfect. Are not IEMs that are faulty generally faulty across the board? They are not due to how the music is produced. The simplicity here is they replay, really good recorded music. Playback is with-out fault. I mean there is a hint of the character they are known for being bad with, but in this case it’s an attribute strangely enough. The sound is big, involving and pure. Way too pure for the humble cost of $79 dollars. So the question is what other music is bad and what else is good? But before we get to that.........a song. Not just any song but mother of all test songs. A song held in such high regard by yours truly that it has become one of the ultimate litmus-tests. The single event which by many accounts holds the highest honor of playback here at Redcarmoose Testing Laboratories. And you guessed it.....playback is spectacular, at any price!

The bass hit the first second of playback is from the previous song. After the cello and violins we are left with a single synth timing everything. This become the single metronome for the entire sequence. Hans Zimmer is a genius, and that’s not an area of speculation, he is a real musical genius. Because at the 2 minute 6 second mark he has arranged a bass drop so big and deep it’s omnipresent. Such a drop shows timing with our metronome. But hold-on I’m getting ahead of myself here. Let’s rewind.............

At 41 seconds the reoccurring theme is once again reintroduced. A single piano is our center of attention. Yet as the song progresses there is room for other accompaniments. But the first 30 seconds of the song had no metronome at all. Though if you go back to the start you will absolutely feel the pace provided by the metronome which appears 30 seconds in. Maybe we are listening backwards now?

Anyway I just vaguely remember this part of the movie. It’s also interesting when Bruce Wayne exposes Batman talk while still as his regular self. This single backset synth that starts at about the 30 second mark is our anchor. Such a device will become a backdrop for the actual piano keys. Such a slight song reminds us of the continuation of the movies theme. Orchestra extras make their way in and at 2 minutes 6 seconds we are reminded that we are listening to a Hybrid. Oh, wait I haven’t really used that word in this review, except that is what’s going on. One driver for the highs, and a separate driver for everything else. This bass drop is the real deal. It’s almost world-class. Somehow none of any of our issues are noted or heard. But there is more. The more is the fact that there is bass texture?

Also at 2 minutes and 39 seconds there is a bass rise. Such an effect they use to allow the synth envelopes to open and allow a slight boost of bass quantity. It’s a fitting end to our test and if you ever listen to this soundtrack as a whole it’s actually a set-up also for the next song. These songs are all pieces of a bigger fabric statement. Broader than what could take place with our little 3 minute 27 second song. You see the music is the glue. The music goes to piece all the unconnected photography. What seems to not go together is fully sewn together for us by the soundtrack. Such are the tools at hand and the importance of each piece of music being interlocked.

Looking for trouble:
So as promised I’m going to go out and look for trouble. Truth to be told I found a lot more stuff that the Mermaid MM2 did well? The 75 hours of burn-in may have helped quiet the angry bees. But no there is no stopping them, obviously lowering the volume to library levels works, but who can read when Rammstein is playing? This is a good example of what we are dealing with here, while buzzing and cool, better IEMs playback the rhythm guitar better. It’s just slightly off. So it’s both buzzy and off-tone.

Example 4:

Armee der Tristen:

44.1 kHz - 24 bit

Mind you this guitar is buzzy anyways. Such a sonic novelty is very special and it’s sad but the Mermaid MM2 lays buzzy on top of more buzzy and we get stung. And while as a whole this album is great playback, except this is a review and the reason your here reading. So in typical Hybrid fashion we do get big separation of musical elements. That in and of itself is great, except the forwardness of things go to reveal the issue even more. Kind of like you are at a party and your wife wore mismatched socks, and you didn’t want anyone to notice. Here (in essence) is the Mermaid MM2 (as your Wife) taking off her pants and dancing to the music.

The mistakes here are not brushed under the rug, except become this style of double edged sword. So the IEM is great because of them but simultaneously it’s an issue.

Example 5:

And Love Said No:
ALAC 44.1 kHz - 16 bit

Ok, I didn’t go far to find this. It has this forward electric guitar that just like the Rammstein song is front and center. In fact it’s 2X more front and center. Which remember the party senerio, well more even more of that. Though the next song has more buzzy guitar, and I have listened to this for years and years. And while not exactly the right tone or timbre it is kinda fun.

Where this seems somehow not to be a blanket phenomenon. But it kinda is. These IEMs have been a great investment in time and money for Hidizs. Just the fact that they have truly gone all out to market such devices. In fact almost getting a pair out to any reviewer (and his mother) who would take a pair says something about marketing in 2022. And they have done much of the footwork for success. They included a nice package of extras for the money. They have fabricated a shell design which is unique and eye catching. They have included a system to alter the playback to suit the listeners subjective tastes. They have included a great plastic box that no-matter-what you will keep and not throw-out. They have included a nice carrying case. The Mermaid MM2 comes in silver and a Batman Edition too. That’s called black. And I keep going back to my favorite albums looking for issues but there are none. None!

The Sound:

The Mermaid MM2 Treble Experience:
First and foremost I would like to introduce the 6mm Magneto-Static treble driver. It is truly a real add, and in so making the Mermaid MM2 unique in the IEM marketplace. Meaning it’s not some repackaged technology. Except that it is an old technology for home speakers simply brought over for the first time in an IEM. Such an innovation brings with it 2 styles of personality. One, and my favorite part is a style of treble separation. Just as planar, EST and bone condition all bring their very own sonic signature to the table, to name a few. Magneto-Static actually offers a true all-to-itself quality. The treble is actually separated in the treble band into its own zone. Such a display offers the listener a unique and profound way of doing (as an example) high pitched “tambourine” or other add-on “shakers” added on as an embellishment to the basic rhythm. An extra kind of trigger to add to the full-scope and excitement going on. A basic example would be the crash cymbal. Such a pedestrian instrument yet when placed into the mix appropriately can fully add to the music at hand. And the Magneto-Static does in-fact do a job. These cymbals would never normally be existing in such fashion or form, and for that I am grateful. Being a novelty or a true added workhorse to the full-on display is up to subjectivity to fully describe. Is it always off........... no. Though when we travel down the playback scale of instruments that have the true quality of containing more timbre information we are met with a slight brashness. At times it’s not really that bad but take a buzzy treble-centric offering like electric-guitars that were in placement to exploit such tones and harmonics and we are met with a less than perfect style of playback. Though for the money and out-and-about town for a cheap thrill it’s not that bad. Again though it’s an album by album phenomenon. It's a song by song phenomenon too. So in my sessions I found playback to be almost fully removed of such shenanigans, then other times a full-on off tone. The third level as mentioned is when a purposely bright and distorted guitar is taken through the roof with this effect. So it’s not just a tone artifact but maybe an intrinsic way the “tweeter” finds it’s way of doing treble playback?

The Mermaid MM2 Midrange Experience:

Thankfully there is a nice display of mids. Really the mids are the most important aspect of any IEM. There is also kinda a unique character here also. A grainy at times replay, that seems to double-up with a layer of smoothness. Meaning yes, I’ve heard smoother IEMs. Still the imaging is intoxicating and bearable for what it is. All I can say is if I was bored seeing the same, same replay I am at least curious here.

It's different and not all different in a bad way, but different in “I have never heard an IEM like this” way. Also there can be two styles of different as far as midrange goes, with the best different not having too much pinna gain, and that my friends is actually the midrange we have. So it’s with an off combo of music that brightness rears it’s head, even a little in the midrange too. Many IEMs are like this, but here maybe the Mermaid is slightly more of a particular eater. Feed her her diet of the right food and she will refrain from cranky-ness.

The Bass Experience with the Mermaid MM2:
The 10.2 Dynamic Driver does what you would expect it to do. OOTB it came slightly off and slow, but burn-in really changed it for the better. My favorite part you ask? This is in fact my favorite part of the entire replay and worth way-way more than $79 dollars. In fact it is worth putting up with any temperamental psycho-acoustics put out in random intervals by that terrible treble maker. It is in fact incredibly well done secret bass. A hidden bass that shows a pedigree only found by a few super-stars in the IEM world.

Hidden Bass: :dt880smile:
My favorite part of listening to IEMs, only I hardly ever get it. And I want it, but you know how things go. It’s always those elusive hidden things in life, that are rare and greeted with surprise when they occur. It’s a super deep yet tuned sub-bass. It waits and may show up only when all the parameters are right. It’s hidden because it jumps out of nowhere and gloriously surprises even the most jaded of listeners like moi!

The rest of the bass is average for the price range if not a little blurred and holding all the quality this price bracket is now known for. I mean let’s face it, the bar has been raised to another level in this price segment. And truly the bass is not really the focus of what this IEM is about. Don’t get me wrong the hidden bass is both eloquent and sophisticated, but the rest is average. When I say average I mean it is fully extended, just not totally detailed but nice. Probably the saving grace here is that there is room in the soundstage for everything to be represented well. I mean I will give the Mermaid MM2 that. The fact that this bass has it’s own areas to exist in even though it’s not the last word in timbre detail. But it’s fine.

How does the Mermaid MM2 do with poorly recorded music?

Interestingly and issues here are with top-notch recordings. Bad recordings actually get a nice level of involvement. It’s actually surprisingly refreshing and a major boost to the intrinsic value offered here. Laughingly old thin stuff actually sounds remastered? Also even bad recordings still offer hidden bass and the rest of the soundstage charms. Even the buzzy replay somehow goes to make a purse out of a sows ear? The buzzy part actually adds to the harmonics as if it is enhancing them and bringing them farther out and up into focus? Then the imaging takes the sound elements and brings them into this big soundstage to once again increase the Illusion of stuff being audiophile? I mean there is a whole section of audiophile IEMs that leave stuff to exist as it is. We often pay a high price for critical playback chops. Though here we are strangely met with a style of excavation of old thin sounds. That and they really don’t sound 1/2 bad anyway? It’s this playback that makes the best of old and dated music, while not altering the tone and timbre.......well maybe a little?

Still while not perfect, modern top-end OSTs will always show you the Mermaid MM2 actually prefers an expensive diet of the best ingredients, yet when the opportunity lends itself, she will make the best of old songs, surprisingly enough!

Technical Specifications:
  • Driver Configuration : Hybrid Driver Configuration 1x MS BM + 1x DD
  • Magneto-Static Type : 6mm dia. Low Voltage Magneto-Static Balanced Membrane Driver
  • Dynamic Driver Type : 10.5mm dia. DD with a PEK Macromolecule Polymer Diaphragm
  • Frequency Response : 20Hz-40kHz
  • Sensitivity : 104dB±1dB@1kHz
  • Impedance : 18Ω@1kHz
  • Rated Power : 5mW
  • Cable Material : Hybrid 4Core Wires Cable (2×High Purity Silver & 2×OFC Wires)
  • Cable Length : 1.2m
  • Plug : 3.5mm

Source Comparisons:
Sony 1A: 4.4mm and 3.5mm
Sony 1Z: 4.4mm and 3.5mm
Apple iPad: 3.5mm

MacBook Air: 3.5mm

ipad 2.jpg

The reason different source components are important here is I’m basically calling the Mermaid MM2 finicky. So if it and why. Many reviewers (previously) said the Mermaid MM2 was not altered too much by upgrading your source. I’m here to buck that claim in that I noticed a huge difference between sources. So much so that it inspired me to write this section you are now reading. I have used the same included cable for all 3.5mm tests. I have used the HanSound Zen OCC in 4.4mm for the balanced test. I used the included narrow-bore tips for 100% of the tests. Though 90% of my review included the use of Sony Hybrid Tips. I also never use EQ.

Let me just say this right off, the Mermaid MM2 does change with source alteration and in many ways it also stays the same. But it does scale-up with better gear substantially. Though this is one of the rare instances when 3.5mm output of the Sony DAPs was actually preferable. Reason being the Mermaid MM2 is naturally kind of intense and doesn't need the extra contrast and dynamics brought on by the separate 4.4mm amplifier in the Sony players.

Also while the DAPs increased soundstage and clarity, my main goal here was to see if the Mermaid MM2 was nice and friendly from the iPod. The main question here is actually what can the Mermaid MM2 do if you only had a computer of iPad to use.

Coincidentally I also had the many of the same songs I used for the basic sound review, which made zoning in on various playback personalities critical. I mean why do a sound review with only one source....right?

Apple iPad:
Well, the great part is the over all musical interaction here. The soundstage is big, but not quite as big as the DAPs. There still is that treble/midrange personality from the 6mm Magneto-Static treble driver. Though I definitely could see how someone would be impressed in a shop listening to these. They have a true immersion experience just due to the size of replay. This is definitely a Hybrid Experience. Probably what works is the pace here, if anything PRaT is one of the great contributing factors. Though the bass is by far more reserved due to the more linear Apple iPad comparison to the Sony DAPs.

MacBook Air 3.5mm:

Remember when I said the Mermaid MM2 is finicky. Well, the flip-side of the coin is that it can be absolutely great from some sources, don’t ask me how or why but it just is. I listened to TDSotM in hi-res and it was fantastic. No issues at all, none. I then played “Bush” 2015’s Snoop Dogs famous bass exploration record and (yes) the bass was amazing, even the vocals were perfect. It was such a distraction that I almost didn’t finish this review, it was totally hard to pull myself away from the humble but dynamite combo! Maybe this is exactly what Hidizs used to tune these? All I can say is if you have a MacBook Air and you were looking for an efficient IEM, that’s really really good, this is one stellar choice. You can thank-me later! The two go together like cornflakes and milk!



Sony WM1A: 3.5mm:
Really the sound review section is parallel to this. To sum it up, pick your music. Meaning the Mermaid MM2 will play back world-class playback from choice files, far beyond her humble asking price. But play back some bright guitar or such and be warned, she will not be your friend.

Sony WM1Z: 3.5mm:
Interestingly I have much of the same music on both players. Coincidentally I had the same album already lined-up that I just got done listening to with the 1A. The Sony 1Z is just better in all facets. Deeper bass, bigger soundstage, wider presence and better treble. Reason being is the 1A has a brighter midrange. Again listening to Hans Zimmer The Dark Knight Rises OST. Different day, different ear tips, same results........fabulous!

Sony WM1Z: 4.4mm:
Yes, well..........the choice “The Dark Knight Rises” IS better but going back to the other music is not due to the increased dynamics and contrast that comes along with the 4.4mm amp.

Sony WM1A: 4.4mm:
Same as above only worse in regards to the treble due to the 1A being even brighter due to a upper midrange boost. Though regular great music choices were fantastic with the 4.4mm amp.

Comparisons to other IEMs:

Tipsy TTROMSO PineStone Sea12mm DD $89.00 a 2022 release
TINHIFI T1S 10mm DD $20.00 a 2022 release
KB Ear Lark 1BA 1 10mm DD $29.99 a 2020 release
BQEYZ BQ3 3BA 2 10mm DD $60.00 a 2018 release

Sony XBA-100 1BA $59.40 a 2014 release

The comparison list is formulated simply by placing listening tests of IEMs that are roughly priced around the same price or below. What should be especially of value would have to be the two 2022 releases as one of them is priced almost identical, and the other a “super-star”’priced at just $20 USD!

Every IEM used the included narrow bore Mermaid MM2 tips, and each IEMs included cable used, unless specified. No EQ used. The Sony WM1Z used across the board for the testing.

Tipsy TTROMSO PineStone Sea12mm DD $89.00 a 2022 release:
The Tipsy goes first in line as it was my one of my favorites this year. Here my favorite is to use the WM1A but out of being equal to every set-up the Sony WM1Z was used. The DUNU DUW O3 cables used with 3.5mm tip. Soundstage is bigger than the Mermaid MM2. While the single DD is more coherent, it still offers good treble and amazing bass. My bet is this will end up the best bass out of the test group? Way more forgiving here. Not dull but none of the fireworks presented with the Mermaid MM2 outcome. More silky and friendly. Not as much contrast, some things may fall back and not be in-focus? This is a slower bass than the Mermaid MM2. Still it’s more my bag. The Tipsy TTROMSO wins the match.

TINHIFI T1S 10mm DD $20.00 a 2022 release:
What? A $20.00 IEM going up against a $79.00 IEM? Are you serious? You bet I am. This was one of the great discoveries of 2022. So while it doesn’t have the separation the Mermaid has it’s way better tuned. Yet it falls short in both low-end extension and treble dynamics. Also the TINHIFI T1S can get rather crowded sounding at times. The TS1 does better with slower music.......the Mermaid MM2.....faster music. I truly with we could combine the two, then we would really have something. This is a draw! They are both equally good at what they do. Though if you read on I give the T1S a great score due to it’s being well rounded. Where the Mermaid MM2 is of course finicky. Still it is a tie.

KB Ear Lark 1BA 1 10mm DD $29.99 a 2020 release:
The Lark! Really some reviewers didn’t get the same build maybe as I? I don’t know, the Lark was heard very differently by various reviewers. Amazingly the Lark is as if the T1S and Mermaid MM2 went and had a baby! It’s a Hybrid with all those characteristics of a DD and single BA. The thing is the Mermaid bass is actually maybe better, it’s slightly tighter. The soundstage isn’t quite as big maybe as the Mermaid? But the main thing is the Lark doesn’t have that brightness. Still that brightness IS definition and clarity. I hate to say it, but it turns out that the Mermaid MM2 despite her flaws is more exciting! Still the Lark will always hold a place in my heart for being one of the first really really good value IEMs I found. The Lark is more well rounded, it stays it’s boundaries better, still maybe pizzazz it what we are after? More pizzazz with the Mermaid? The Mermaid wins.

BQEYZ BQ3 3BA 2 10mm DD $60.00 a 2018 release:
Not using original cable, I think this is a BLON cable. Anyways the Mermaid MM2 tips fit it great, in-fact the (included) tips have somehow fit every IEM in this test today! Well the BQ3 has an off tone/timbre that makes the slight issue with the Mermaid nothing! But the BQ3 bass is quantity only. Missing is some of the texture the Mermaid MM2 brings. Also it’s simply not a vary balanced response, this is really bass-head style. Funny how these few older IEMs are making playback the Mermaid MM2 does stand out as really good? Mermaid of course wins here.

Sony XBA-100 1BA $59.40 a 2014 release:
This is an incredibly inefficient single BA from Sony. It may be inefficient but it still does cool stuff. Still the Mermaid has it beat for being slightly more flamboyant and bombastic. Bombastic goes along way to even beat out a careful and prim and proper conservative response like the one the XBA-100 has. The Mermaid is just bigger in replay, also there is a slight distortion where you can tell the single Sony BA just can’t handle it all. It’s trying it’s best but the Mermaid has a way about her, a vibrancy that the XBA-100 can’t touch. Mermaid wins again!

The Package
-Hidizs MM2 Earphones 1
-Tuning Valve 3 Pairs (Treble, Balanced, Bass)
-Single-Ended 3.5mm Earphone Cable 1
-Eartips 3 Pairs
-Leather Carrying Box 1
-User Manual 1
-Warranty Card 1



storage .jpg

This is singularly one of my most favorite parts........yep this empty plastic box. When you have taken everything out of it you get a reusable box instead of a bunch of throw-away paper and cardboard. No one would throw this out. In fact it's super valuable to me as a storage case for the IEMs.


Made with German resin the form factor is truly comfortable. The solid aluminum faceplate is amazing! There is a valve on top of the faceplate and another facing inward which you can see in the picture below. While maybe it's almost too revealing as every detail of the inside can be seen; even small areas of glue normally hidden by other manufactures. The black model somewhat less revealing as the shell is smoke colored.

mermaid ee.jpg

The cable comes with an actual embossed company name and specific markings to right and left along with somewhat redundant red and blue painted dots. The detachable 3.5mm 2pin OFC cable finds itself with a copper stand OFC as well as a silver plated copper strands. One facet I liked was that the IEM 2-pin connectors were clear plastic as well as totally flush and mount totally flush against the IEM shell when applied.


cable 12.jpg


Comes with a 1 year warranty and free shipping anywhere.
Get them here:
Linsoul website:
Linsoul Aliexpress Store:

Linsoul USA Amazon Store link:

I have to give these a four out of five stars. It’s not a stretch to realize that we are dealing with a company that obviously cares. Truly Hidizs cares. They may just need green valves? Sorry..........just kidding. No, the issues here are the direct result of trying a new addition (to IEM) technology. I would hope that a Mermaid MM3 could offer a more polished and worked-out attempt at rectifying the small issue at hand. Pretty much the rest of the package here is amazing. It makes you wonder if a regular BA would offer a solution? There is nothing wrong with taking a slight step back into familiar waters instead of swimming out to sea, it seems our beautiful Mermaid jumped too soon?

So if you are like me you may find the Mermaid MM2 endlessly fascinating. Why? When it sounds good it is great! I don’t know a better reason to get a new $79 IEM. But also it singlehandedly represents the future. A combination of combined new driver philosophy, combined with stunning new looks and innovative valve system. It has a gorgeous cable as well as a fully realized build. I'm fully intrigued by the aluminum faceplate design and looking-into the German-resin-shell.

Probably the best part is they play back my favorite OSTs flawlessly. They are bombastic and vivid even if their socks don’t match.


Equipment Used:
Sony WM1Z Walkman DAP MrWalkman Firmware 4.4mm/3.5mm
Sony WM1A Walkman DAP MrWalkman Firmware 4.4mm/3.5mm
Apple iPad 3.5mm

Apple MacBook Air 3.5mm

Disclaimer: These thoughts and ideas are of one individual, your results may vary.
Last edited:
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New Head-Fier
Hidizs MM2 Review: The Charm of Three
Pros: One of the most affordable in-ear monitors with variable tuning
Great set of accessories
Good technicalities
Cons: Slight upper mids aggressiveness in the Balanced and Treble valves
Having started in 2009, Hidizs can definitely be considered a veteran in the field of portable audio. Their first product, the digital audio player AP100, was launched three years after the company was founded. And now, a decade later, Hidizs continued to progress and vastly expanded their product offerings. The MM2 is the newest addition to their lineup of in-ear monitors. This one features a total of three tunings through the replaceable tuning valves. As of writing this review, the MM2 retails for 79 USD, and was provided to me for free by HiFiGO in exchange for this review.

International purchase link

Driver units: 6 mm low voltage balanced membrane magnetostatic + 10.2 dynamic, polyetherketone diaphragm
Impedance: 18 ohms
Sensitivity: 104 dB
Frequency response range: 20 Hz - 40 kHz

Poco X3, Redmi Note 10 Pro paired with Cayin RU6, Xduoo Link2 Bal, FiiO KA3, Tempotec Sonata E35 and Zishan U1

Test tracks:
Africano - Earth Wind and Fire
Dark Necessities - Red Hot Chili Peppers
Gurenge - Lisa
The Chain - Fleetwood Mac
Monsters - All Time Low
Ours - Taylor Swift
Stay - Mayday Parade
Snuff - Slipknot
Yesterday Once More - Carpenters
So Slow - Freestyle
Aurora Sunrise - Franco
Attention - Pentatonix
Blue Bird - Ikimono-gakari
You're Still The One - Shania Twain
Anyone Who Knows What Love Is(Will Understand) - Irma Thomas
Salamin - Slapshock
AOV - Slipknot
Hey Jude - The Beatles
The Way You Make Me Feel - Michael Jackson
...and a lot more.

Unboxing and Accessories:
The MM2 comes in a relatively medium sized sleeved black box. Removing the sleeve reveals a hard plastic inner box, which is nice because it can be reused more than the regular cardboard boxes. Inside, there are the earphones inserted in a piece of foam. Below it is a smaller box that contains the leather case, and inside that case are the chunk of metal that holds the Bass and Treble tuning valves, a small silica gel packet, and two sets of silicone eartips. One in medium sized bores, and another with wide bores. Underneath the foam, there is another box that contains the cable with a velcro strap. There is also an instruction manual, a warranty card, and a card for Hidizs' website information.

The shells are made of resin, with a metal faceplate and nozzle. The faceplate has this kind of a polygon design with a matte surface. This is also where the valve is situated, which is kind of unusual since a replaceable nozzle is what's commonly implemented. The valves are also made of metal and classified with their color. Rose gold for the Balanced, red for Bass, and silver for Treble. There is a small vent right below the female 2 pin connectors, and another one at the back side of the shell. The nozzles are equipped with a recessed metal filter and a lip to hold eartips in place.

The cable is a 4-core twisted hybrid of oxygen-free copper and silver plated copper. There is only very minor microphonics. The cable is also very soft, light, and with good flexibility. The angled 0.78 mm 2 pin connectors are made of plastic while the splitter, chin slider, and the 3.5 mm gold plated plug are all made of metal.

I will be using the Balanced valves for the sound impressions, and then compare it later against the Bass and Treble valves.

Now let's get to the sound.

The lows are partially boosted and smoothly textured. Subbass is reproduced with very good depth, alongside a decay and amount of rumble that are both just slightly above average. Midbass is also emphasized to some degree and shares the same weight as the subbass.

Overall, the MM2 has your usual type of lows in a warm sound signature. It can also be noticed that the texture here feels smoother and cleaner than other in-ear monitors in the same price range.

The mids display great clarity and are a tad forward. The thickness of the lower mids is pleasantly accentuated, but the notes become thinner and thinner as it shifts to the upper mids. As a result, female vocals are positioned slightly ahead of the male vocals.

Overall, instruments have good transparency in this section. The lower mids are great for classical music, and while the upper mids does get a little shouty on some tracks, it is only minuscule and nothing to be worried about.

The highs provide an adequate amount of energy. Treble reach is decent with an average level of decay. There is a subtle highlight in the lower treble but on some tracks, it is not enough to bring out the vibrancy in the instruments especially when a number of them starts playing in the background.

Overall, on its own, MM2's treble is actually good. But the upper region of the treble can get overwhelmed sometimes by the upper mids affecting the details and general technicalities.

Soundstage and Imaging:
There is moderate expansion in the soundstage. Width is just average but the height has really good amount of space. Imaging accuracy is very good, different instruments can be identified and their positions pinpointed with ease. Congestion is very minimal even in busy tracks.

with the Bass valves
The Bass valves greatly improved the depth of the subbass. Decay is also slightly more extended. The amount of rumble is of course increased as well. Midbass became thicker but not too much to the point where it feels bloated. Mids are pushed down a bit, and that bump in the upper region is now smoothened. Treble reach and extension stayed the same. There is a slight reduction in the height of the stage, but the width and other technicalities did not change.

with the Treble valves
There is a very slight decrease in the depth of the subbass while the decay became slightly tighter. With the midbass, there are no changes. The mids are still slightly forward but the thickness of the lower mids is reduced, and then the upper mids became even thinner, amplifying the minor shoutiness from the Balanced valves. The reach in the treble is improved. Decay also became partially longer. Instruments are now livelier and more crisp. The stage widened a bit, and the imaging became slightly clearer.

Hidizs MM2 with Balanced valves (1 magnetostatic + 1 dynamic, 79 USD) vs. KZ ZES (1 magnetostatic + 1 dynamic, 32 USD)
Depth in the subbass seems to be equal, but the ZES has more quantity in the rumble. The ZES also has the longer decay, but not that much difference. The MM2 though, presents smoother, cleaner note texture. The MM2 also has more forward mids, but the ZES has slightly thicker note weight. Instruments have better definition and sound more spacious in the MM2. With the treble, the ZES has slightly better reach, but they are equal in terms of the decay. That being said, the MM2 still manages to present details clearer due to its overall better technicalities. Imaging is a lot more clearer in the MM2, as well as better instrument separation. In the soundstage, the ZES has the larger width, but the stage is taller in the MM2.

Hidizs MM2 with Balanced valves (1 magnetostatic + 1 dynamic, 79 USD) vs. IKKO OH2 (1 dynamic, 79 USD)
The MM2 can certainly reach deeper in the subbass. Rumbles are also more powerful and extends longer in the MM2. Midbass punches harder and with heavier, thicker note weight in the MM2. The positioning of the mids are identical in both of them, but the mids in the MM2 can sometimes be perceived as slightly more forward due to that bump in the upper mids. Lower mids are thicker in the MM2. The MM2 also has slightly better reach in the highs. The decay is almost equal but the MM2 presents a very, very tiny edge. The OH2, on the other hand, has slightly better presence in the lower treble. Imaging clarity and accuracy are identical, as well as the width of the soundstage, but the stage of the MM2 is slightly taller.

The magnetostatic driver is not something new in the world of portable audio, but Hidizs managed to give it a new twist in the MM2. The way they implemented the tuning valves sure is attractive, especially at this price point. The Bass valves do give the MM2 the hard hitting lows most bassheads seek, but it's a little confusing that the MM2 is already warm sounding with the Balanced valves, and the Treble valves did not sound the way that I expected them to be. For its asking price, the MM2 surely performs well, and the tuning valves is a great idea by Hidizs, they just fell a bit short with the execution.
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Headphones and Coffee

Previously known as Wretched Stare
Good for the cost
Pros: Good balanced signature goes well with all music. Bass has control and speed, accessories are above its price range in both quantity and quality. Looks good and valves allow some customization of sound.
Cons: treble needs more energy and the valve screws are tiny and hard to use with my big hands but not impossible.

MM2 adopts a 6mm magneto-static BM (Balanced Membrane) driver customized by HIDIZS and Korea BSE, with an extremely thin and light micron-level diaphragm, Its an unusual configuration that translates to a good sounding IEM that surprisingly cost under $100.

Build ECT.. Packaging is very premium looking with the mail box being made of plastic. Inside one finds.

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.

The Specs are listed as


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, aluminum alloy faceplate, aluminum 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 units themselves are light weight, built well and feel very comfortable to me. I love the faceplate its angled design is very nice in my opinion.

Stock straight out of the box they're balanced and detailed with some warmth and the signature is pleasant and not fatiguing at all.

Bass: Is rapid and punchy with a good rumble in the lower Bass. There is a good control throughout and details in both Sub and Mid Bass. This is enhanced when using the Red filter valves and lessened with the silver.

Mids: Are presented lush and clear with a little warmth in the lower end but still very natural sounding vocals both male and female are good and centered well amongst the instruments. I found the vocals and instrument separation good and male vocals in general were quite pleasant and full.

Treble is relaxed but still retains enough details and sparkle to be enjoyed without harshness or over extension. Still they sound open and have good energy if not a little subdued compared to BA hybrids in this class. Highs are decent but Treble heads will not be impressed.

Stage is open and has a respectable width, Hight and depth for even gaming on the go but stays in a natural area around ones head in and around a 180 degree pattern give or take. separation is excellent and imaging is accurate, this is one of the MM2 strong suite.

Overall: The Hidizs MM2 offers and mix of fun and detailed sound to enjoy music without fatigue and is targeted towards everyone with its safe and smooth tuning and the accessories and build quality just add to is alure.


The case looks pretty. Do you think its a good IEM for rock and metal?


500+ Head-Fier
Valve Innovation
Pros: 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.
Cons: 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.

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.

Hidizs MM2 01_resize.jpgHidizs MM2 02_resize.jpg


  • 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).

Hidizs MM2 03_resize.jpgHidizs MM2 04_resize.jpg


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.

Hidizs MM2 05_resize.jpgHidizs MM2 06_resize.jpg

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.

Hidizs MM2 07_resize.jpgHidizs MM2 08_resize.jpg

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.

Hidizs MM2 09_resize.jpgHidizs MM2 10_resize.jpg



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.

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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.

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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.

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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.

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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.

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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.

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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.

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  • Construction and Design: 85
  • Adjustment/Ergonomics: 86
  • Accessories: 90
  • Bass: 90
  • Mids: 80
  • Treble: 70
  • Separation: 82
  • Soundstage: 89
  • Quality/Price: 85

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Hidizs offered me this model, in exchange for writing an honest review. I want to make it clear that all my opinions written in this review have not been conditioned by this fact, nor will I ever write anything that I do not really think or feel here. I will only write about my personal opinion in relation to the revised product.

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Purchase Link

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You can read the full review in Spanish here:

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