Hidizs MS4 Mermaid

disclaimer:  I was sent the Hidizs MS4 Mermaid and kit by Hidizs for purposes of this review.  I have no financial interest in Hidizs and was not compensated other than the product itself.   If you have an interest Hidizs, you can visit their website or their Amazon store.


Unboxing / Packaging:

I was expecting a small package in the mail, instead I got a large box and 4 smaller ones containing the optional cables, connectors etc.  All arrived in matching flat black packaging with logos in gold on the headphone box and silver on the smaller packages.  Details are written on the reverse of the box in both Chinese and English.   Slipping the outer cover off reveals a lift-top style inner box.  The earpieces with the 3.5mm cable attached rest in a foam tray with the cable neatly tucked into a pocket on the reverse.  Under that tray, is another with a very robust assortment of tips, a spacious leather case, a black cloth bag for carry, and the warranty card.   Overall the kit is quite complete at the price point and the leather hard case is the same style as those used on several other popular models (such as Simgot’s EK3) although the MS4 version is larger.



The MS4 is an all aluminum shell with bright anodizing and gold trim.  The faceplate has a polymer coating that gives it a domed shape and a highly reflective surface.   The Hidizs name logo are emblazoned in gold on the face as well.   Overall, the bright color and gold accents give the MS4 a pleasing look and makes theme almost instantly identifiable among a sea of look-alikes.   Fit and polish is quite good with the junction between faceplate and inner shell being only slightly detected with a fingernail and not detectable with the pad of ones finger.   The .78mm bi-pin connectors is raised and overlaps the shell so no gaps or slop is visible but unlike the current trend, the MS4 does not use the hooded style bi-pin and instead uses a larger than average flat mating surface on the earpiece and the cable to insure proper connections.  Shape is mid-sized teardrop with an ergonomic inner shell shape and a fairly extended section the nozzle sits on.   This results in the MS4 sitting mostly in ear and the eartip being fairly deep seating as a result.  I found myself using smaller tips than normal as a result and both fit and comfort were good once I found a tip of the appropriate size.      Nozzles sit at the lowest point on the inner shell and have a large lip for tip retention and almost no rake in any direction.  Two vents exist one on the inner face and a second at the top of the shell centered below the hidizs Name and L/R.



The MS4 is a hybrid containing a 10.2mm Dynamic driver which hidizs lists as using a patented Macromolecule diaphragm material for more rigidity and less flex along with 3 Knowles made balanced armatures per side.   The dynamic driver handles low end duties while a pair of 30017 balanced armatures handle the mids and lower treble and a single 33518 balanced armature handles the highest of frequencies.     Nominal impedance is listed as 12Ω with a sensitivity of 112dB/mW.   This would suggest the MS4 can be easily driven by a phone or tablet and indeed in my experiencce it works quite well from either of those.    The Ms4 does scale qualitatively with better sources, but is well driven even at fairly low power.   I found myself particularly liking the provided DAC/Cable that incorporates as usb-c connector with the Sonata HD dac at the low end and a set of bi-pin connectors at the top.  When paired directly to a Samsung S9 or Moto Z3 this was a great setup for on-the go use with Tidal or local files.



Normally this section is kind of the cursory required discussion of the included cable, but with the MS4, that isn’t the case.  Hidizs sent no less than 5 cable options.  I received the standard 3.5mm single ended, a 2.5mm balanced cable, a 2.5 to 4.4mm adapter for use with the Sony DAPs, a bluetooth cable for wireless use, and a Sonata HD  Dac cable for connecting the MS4 directly to a usb-c port on a phone or tablet.    Short of an XLR cable options (which seems a bit silly for an in-ear designed for portable use) they pretty well have all the options covered.

There are three different styles of cable construction with the 2.5 and 3.5 sharing very similar construction and the 2.5-4.4 adapter and the dac cable sharing the same cable type.  The Bluetooth cable is different from either of the others two pairs.

Starting with the standard cable, it has gunmetal gray fixtures with very fine knurling on the body of both the jack and the splitter.  The straight 3.5 Jack has a portion at the top that is not knurled and has the hidizs name stamped in white.  The splitter mirrors the jack by using the non-knurled chin slider mated to the top of it.   The north of the Jack and the south side of the splitter also have short strain reliefs to protect the cable.   Cabling is two wire twist from the jack to splitter and is fairly heavy gauge but still remains pliable with little tendency to tangle.   Hidizs lists the wire itself as silver coated oxygen free copper.   At the north end the cables have pre-formed earhooks and .78mm bi-pin connectors with gold plated pins .     The 2.5 cable is a duplicate of the 3.5 with the obvious exception of the jack.

The DAC cable is a bit different in construction.  It starts with a USB-C connector in a black housing, again with a short strain relief, but this time with a 4 wire braid up to the splitter which is a matching black fixture and then exits as pairs of wire up to the pre-formed hooks and the bi-pin connectors.  The individual wires are a bit thinner than the 3.5 cable but still well made and I found myself liking this cable far more than I thought I would.  Sound was very good with stage being almost holographic in nature and well defined in both depth and width.  The Dac itself is recognized as the Sonata HD with the specs listed below.   The cable can be purchased separately as the DH10-RC and works equally well with 0ther .78mm bi-pin in-ears.

SNR114 dB
OS SupportWindows, Android, MacOSx
Output Power2x60mW @ 32Ω
Output Current50mA
Formats SupportedPCM 16/24 bit, 44.1/48/88.2/96/176.4/192 KHz

The 2.5 cable and USB-C cable came with velcro cable ties and drawstring bags as well for storage when using one of the other varieties.  the standard 3.5 came with a cable tie as well but the base package contains a leather hard case for the iems so no separate cable bag was provided.

The 2.5 to 4.4mm adapter has a 2.5mm female jack using a housing similar to those on the 3.5 and 2.5 cable connected to a 4.4mm TRRS Male jack with the same gunmetal housing.  The cable between the two connectors is of the same style used in the USB-C cable so the adapter adopts some of the aesthetic of both designs.

And lastly the Bluetooth cable which sports the CSR8645 chipset that supports Apt-X, Apt-X LL, and AAC in addition to SBC protocol.   The around the neck style band has matching boxes about chin high with the one on the left acting as the battery compartment while the one on the right houses the electronics, mic, and remote.   Battery life was roughly 6.5 hours with a charge time of roughly 2 hours using a standard 500mAh usb charger.   Cable material is listed as oxygen free copper with no mention of the silver plating that was used for the wired versions.    The remote is a three button type with multiple functions per button depending on length of click and sequence and the cable ships with a manual of its own to cover all the possible click combinations.   I found the cable worked well within the limited distance it was designed for and as long as source remained within about 10 meters of the cable it performed admirably.   The signal was easily defeated by walls and even a single layer of drywall was sufficient to cause disconnects.



The package comes with 3 different types of silicon tips in small, medium and large and 3 sets of medium sized foam tips.  The silicon tips come in balanced (solid black), Vocal (black w/red stems), and bass (white).     In listening to the different offerings, I found most did exactly as advertised but changes between tips were slight.    The balanced tip is quite relaxed overall with an emphasis on the mids,  the vocal tip gives a slightly more aggressive upper end and sounds a bit brighter than the more laid-back balanced tip.    I’ve never been a huge fan of foams as I feel they tend to alter the sound signature too profoundly and this was no exception.  For those seeking the most possible isolation, the foams are the best option, but know going in they do change the voice of the MS4.  Moving to the bass tips, these are almost a combination of the features of the vocal and balanced tips.  Bass is emphasized regardless of tip and not markedly increased by the bass tips, mids are a touch forward similar to the balanced, but treble is a bit tighter than the balanced and a bit closer to the vocal in presentation.

I did the tip comparison graphs as I normally do, but found that they showed less on the measurements than I found to be the case when in use.




Balanced tips used for Frequency Response graph.


Sub-Bass is emphasized and delivers good rumble when called upon.  Emphasis centers around the 50Hz range with roll-off becoming evident in the low 30Hz range. Mid-bass drops back from the 50Hz peak and is less emphasized comparatively but still very much present in the mix.   The bass is just a touch slow in both attack and decay, with decay being slower than attack.  This gives the bass some weight and warmth but can also come off as a bit sluggish or dirty particularly as tracks get busy.  While I like the sub-bass emphasis, when combined with a slightly thick, slow presnetation can get boomy at times when basslines get complex and fast.   This wasn’t an issue most of the time but genres that present a lot of fast bass movement may overwhelm the MS4 and it would be worth auditioning before purchase if those genres make up a large portion of your listening.



Transition from mid-bass to lower mids is smooth and more linear than expected with the transition from the dynamic to the balanced armature.    Mids are somewhat V shaped with the true mids sitting in the valley between the drop-off of the mid-bass and the rise of the upper-mids.    The lower-mids have good texture and detail and the added warmth from the mid-bass gives good weight and presence in the mix.  True mids are slightly behind both upper and lower but remain well represented with good timbre.  Upper-mids climb subtly forward before dropping back as they move into the lower treble.  This provides good presence with none of the harsh side effects so often seen with upper-mid/lower treble elevations.   The push of the upper and lower regions combined with the level of detail presented moves vocals to the front and allows them to take center stage without hiding instrumentation or dominating the overall signature.



Treble on the MS4 is a very different style than most in its price range.   Most have an upper mid / lower treble push and then fall quickly above that, the MS4 instead has a slightly recessed lower treble and then a push back forward for the true or mid-treble range before finally rolling off a bit above 14kHz.    This makes attack a bit milder than those with the lower treble boost, but instead gives the MS4 a very non-fatiguing signature while still maintaining an open sounding top end.   Detail and clarity are not sacrificed either as a result of the later push.   Snare rattle is satisfying, and cymbals are not splashy or metallic.  Something about the tuning gives the Ms4 more top end air and space than one would expect with the roll-off where it is, while not a common tuning, I have to applaud Hidizs as it is a very practical one.


Soundstage / Imaging:

The ms4 stage is better than average in depth which seems a bit odd for vocal forward in-ear and especially when combined with a width that is much narrower by comparison.   Depth is nearly class leading while width is only average at best for iems priced in this range.   Instrument separation is above average and I found seating the orchestra was mostly correct with what seemed like an occasional mild overlap.   Imaging can suffer at times because of the bass delay, and spatial cues are easier to discern when they are presented in the higher voices as the lows sort of expand to fill a larger space which makes finding exact locations harder.    Layering is good, but again at times the thickening of the bass can obscure things above it.



The obvious pairings for the MS4 are the Hidizs DAPs so I started out my listening with the AP200 and went from there.    The AP200 has good synergy with the MS4 as the dap is a bit relaxed and smooth with a bit less bass emphasis and helps to tone back the bass peak slightly.   Mids are well rendered with plenty of detail and the treble is well presented without fatigue.    Overall, the combination of AP200 and MS4 make a very forgiving pairing that delivers good dynamics and detail while still smoothing over a few rough edges, and the combination would be a good option for someone with a fairly large collection of fairly poor recordings  (and lets face it, who among us doesn’t have those lurking in our collections).      Hidizs has since let me know they are sending an AP80 dac to test as well so I will write it up and post notes regarding synergy with it as well.

When paired with the WM1a which has a slightly more clinical leaning, the MS4 is a bit less forgiving, but detail does improve and a few of the slight exaggerations in tonality that were present when paired to the AP200 drop back into a more natural position.   I used the WM1a to test the 4.4 to 2.5 adapter as well and found it worked without incident with no loss of signal if twisting the connector between the 2.5 cable and the adapter.  (I have found this to be a good test as less connectors sometimes come in and out of contact as you spin the jack).

I paired the MS4 to an android phone (Moto Z3 Play) using the USB cable and both Tidal and USB Audio Player pro and really enjoyed the result.   The built-in Sonata HD dac/amp provided more than enough power and detail rendering with this combination was not markedly behind the AP200.    This combination also seemed a touch smooth, but worked well and honestly was probably the biggest surprise of the review for me.   I came away thinking I could use a couple more the of the USB-C cables to use on other in-ears.   It is a product I think Hidizs would do well to advertise more as I think it offers a great solution for those who no longer have a 3.5mm Jack on their phone to use with their old favorites.


Thoughts / Conclusion:

Hidizs is a company that has sort of flown under a lot of people’s radar.  For quite sometime now, they have been making good DAPs in the budget segment of the market, and have more recently come out with a very solid little dongle for use with today’s phones.   They make both an internal and an external PC Sound card that test very positively and offer very competitive features at modest prices as well.   So the company has a history in the Audio market, but what they haven’t done until now, is make their own earphone or headphone.    To me, that makes the MS4 even more impressive.  It’s hard to make a great iem, its even harder to do so when you don’t have the benefit of past experience to help you.    The MS4 isn’t a perfect product, but it sure comes closer than I would have thought it could for a freshman effort.    Shells are superbly well made and polish is second to none,  Sound signature is unique and in many ways quite practical as it gives good end to end extension without the usual fatigue that comes with it.   Kit is among the best at its price point, and connectivity options are easily the most complete collection I have seen at anywhere near this price  (The kit rivals that of the RHA CL2 that was closer to $1k than $200).      It falls back down a bit due to a dynamic driver that could use a faster reaction time as attack is a bit blunted and decay is a bit too slow and can make the low end a bit thick at times.   That isn’t a huge flaw, but it is present and will be noticed at times while listening.   Overall, I’m impressed with the MS4, and even more impressed with Hidizs for bringing forth such a solid foundation to build on.    I’ll be at the front of the line to buy the MS4ii when they put in a faster dynamic driver to cure that speed issue as I think that will take a great 1st effort and turn it into a truly great in-ear.

Hidizs MS4 Mermaid




Build Quality




Sound Quality

  • 7/10
    Bass - 7/10
  • 7.5/10
    Mids - 7.5/10
  • 7.5/10
    Treble - 7.5/10
  • 7/10
    Soundstage - 7/10
  • 7/10
    Imaging - 7/10


Pros –  Build quality and Accessories, lots of connectivity options, W signature with clean mids and treble that is both well extended and mellow.

Cons –  Size is on the large side and may be an issue for small ears, bass is a touch slow, overall signature may be too laid-back for some.