Sony IER-M9 In-ear Monitor Headphones


500+ Head-Fier
Pros: + Superb fit and comfort. Extremely lightweight.
+ Superb isolation
+ Incredibly coherent and well-balanced
+ Versatile tuning
+ Vigorous DD-like bass. Robust, impactful, defined, taut, with near-DD decay. Significantly tauter, more defined, more authoritative, and more impactful than the Sony XBA-Z5.
+ Fantastic soundstage across all dimensions. Not quite as ‘out of your head’ as the IER-Z1R, but incredibly satisfactory nonetheless. Much larger than the Sony XBA-Z5 and Campfire Andromeda OG.
+ Open, spacious presentation
+ Ultra-precise imaging
+ Impressive instrument separation
+ Remarkably, effortlessly resolving
+ Great speed
+ Outstanding treble extension and detail; crisp, airy, and refined
+ Great value
Cons: x Lacks the dynamism and physicality of DD bass
x Lacking in 'fun factor'
x Somewhat hard to drive
x Sensitive to tip selection and insertion technique

Spotify Premium on Mac > iFi ZEN DAC Balanced > iFi ZEN CAN Balanced > IER-M9 w/ Sony Hybrid tips + 4 Core 22AWG OCC SPC Litz 4 cable

I'll keep this brief:

My main drivers over the past year have been the 2014 Sony flagship XBA-Z5. Despite their age, I've yet to encounter anything around the $500 price point that matches their unique speaker-like presentation. I'm primarily a bass and soundstage head, so the Z5 fit the bill nicely, but I wanted to more out of them technically.

I bought the M9 blind, and kept my expectations checked, having read that they didn't match the Z5 in terms of soundstage, and having found the tonality of the all-BA Fearless S8F decidedly uninspiring despite its V-shaped tuning. I had also previously owned the AK T8iE MKII and extensively auditioned the Campfire Andromeda OG, and was frankly underwhelmed by their performance given their entry price.

Let’s just say the M9 has single-handedly disabused me of the notion that TOTL IEMs offer only “incremental refinements” above mid-fi units. To my ears, the M9 sit confidently in a class of their own, just below the IER-Z1R, and well above the AK T8iE MKII, Campfire Andromeda OG, and Fearless S8F.

Crucially, as several users have noted, the M9 are especially sensitive to tip selection and insertion technique. From my listening experience:

Non-ideal fit = Stuffy, overly-warm, thick, laidback, blunted transients, small soundstage

Ideal fit = Clean, quick, precise, open, airy soundstage, extended treble

Due credit to @CoryGilmore for the following tips:
  1. Use the smallest sized tip that provides the deepest possible insertion and seal without creating a vacuum/suction effect
  2. Pull the top of the ear up and back when inserting IEM—this minimises pressure from within the ear canal, and mitigates the vacuum/suction effect.
Highly recommended.
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I had the same issues with insertion, it was a hassle of 3 days to find the right tip size.

Additional tip: After they are inserted, quickly jiggle/wiggle the unit while softly trying to push them further in. This sometimes helps them getting more inside without creating under or over pressure.

Sounds silly but works awesomely good. This tip is actually from the Sony Manual :D at least the japanese manual says to quickly jiggle/wiggle them around to get them deeper inside without creating any preassure.

You know that they are properly inserted when the sound doesn't (or only very marginally) change when you mover your head around, raise your eyebrows or tension your jaw muscles by biting.


100+ Head-Fier
The Overlooked Silent Assassin
Pros: Soundstage
Instrument seperation
Incredible vocals
Cons: Very very infrequently upper mids shrills
The Sub 1k IEM market is one which has heated up ferociously in the last few years. Especially with the likes of Chi Fi manufacturers getting traction and even starting their own cult house SQ etc. Makes finding a good bang:sound IEM increasingly difficult.

I have been on this mission for the last 2 years (see my previous reviews). I've been through pretty much all well known manufacturers from 64 audio to campfire audio to beyerdynamic and Sony.

Every time I thought i'd found the one, i'd find myself finding flaws in the SQ or loose interest shorly after.

Right off the bat, these are not neutral nor as some have purported sterile. They are warm and have a slight bass boost.

Now take this with a grain of salt (i'll edit the review later if it changes over the next few weeks), but, the Sony IER M9 are hands down the best most coherent sounding IEM i have ever heard.

- MBP - 3.5mm
- E1DA G3 - 4.4mm
- Tidal Master
- The M9 even though rated at 20 Ohms responds remarkably to amping, the more power you give them the better and better they sound (much like the Z1R). Balanced is the way to go to power these.

Music Tested:
- Pop, Hip Hop, EDM, Rock and occasional Indie

Unboxing + Accessories:
- Blows everythign sub 1K (aside from the beyerdynamic Xelento which is on par) out of the water. Class act by sony
- Cables are great.
- Nit picking, the case like the Z1R is over engineered and stupidly annoying to store.

- Very easy to get a good seal and good fit. The IEMs themselves are very light and contour naturally to the concha.
- The selection of tips allows a fit for everyone, silicone tips do produce at times a negative pressure effect due to venting on the IEM - can be circumvented by superiorly tugging your ear when you insert the M9 or doing a valvalsa whilst it's insitu.


- Bass (9.5/10)
eing a self confessed bass head this was my biggest fear getting these IEMs that the bass was going to be lackluster and trash compared to DD bass on the Z1R.The bass on these are exceptional for a BA. Very much comparable to DD bass. These sound nothing like other BA bass (that is the CA Andro's), the bass is thick has a decent amount of rumble and even has the subwoofer effect. Sony have done something marvelous with their inhouse BA drivers. The bass is fast and has great attack. Precise. The only better Bass (technicality wise that is, not quantity) is the Z1R which had even better sub bass extension and rumble. Plenty of other DD and hybrids with more Bass quantity, but none this well executed (if you don't believe me listen to Take me back to london by Ed Sheeran). If the song has prominent bass, you get prominent bass. Never bleeds into mids and is suberbly executed. Well done Sony. -0.5 for the comparitvely less sub bass extension (i know not possible for a BA, but still)

- Mids (9.5/10)
The best vocals i have ever heard on a pair of IEMs, bar none. These outperform the Z1R in the mids easily. Male and female vocals are superbly executed, crystal clear with no distortion. High octave female singers can sound slighly blunted at times, but again minor caveat. On the very rare occasion the upper mids sounded shrill and artificial, however this seemed to be track specific. -0.5 for the occasional shrills (i need to reitorate, very infrequent, maybe more related to track mastering as it was only on 1 to 2 tracks out of 50)

- Highs (10/10)
I've never really been able to assess highs very well. I'm extremely treble sensitive so take what i say here with a grain of salt. The highs are clear and at no point in any tracks was there silibance or harshness. No matter how high you turn up the volume. Cymbals sound accurate and precise. There isn't much ariiness (compared to the Andros) but i never really cared about that.

- Soundstage + Seperation (10/10)
The best seperation out of any of the IEMs i've heard. The layering is simply exceptional. From memory the next closest would have to be the Tia trio which also had great seperation and layering, but after time sounded boring and unentertaining. The sounstage is wide, vocals still sound intimate but not in your face. The coherency is outstanding. These are very easy to listen to for extended periods of time without being being fatiguing.

I think i can finally say i have found my endgame IEM. These are simply outstanding. I've gone through so many IEMs which i would keep for a week, a month and sell on. From the moment i heard these i knew they were the ones that will never get sold on. Unfortunately i don't have the previous IEMs to directly A/B but from memory these are a carbon copy of the Z1R with less bass, better mids and substantilly better highs - that is i found the Z1R sibilance unbearable. These easily beat out the CA Andros, Alas, Vega , 64 Audio Tia Trio, EE Legend X, Beyerdynamic Xelento and even Sony's own flagship Z1R. For me this is now the TOTL benchmark.
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Headphoneus Supremus
Pros: Outstanding mid-range and coherency
Great imaging
Comfortable, lightweight, good build quality
One of the better cables out there + 4.4mm included!
tip selection and case
Cons: Minor nitpicks: slightly too warm for my tastes

The Sony IER-M9 originally came out at the MSRP of $1499 but has since dropped down to $999 in recent months. This puts in the shouting distance of other multi-BA IEMs like the Hidition Viento and the Moondrop S8. Unfortunately, I have not had a chance to hear the S8 yet, but I was very excited to try the IER-M9 and see how it stacks against my custom Hidition Viento-B.

This unit was sent on loan to me by community member, tma6. Thanks!


The IER-M9 is a 5-Balanced Armature driver in-ear monitor that features a black magnesium housing with a carbon fabric looking decal in the front. The shell is very lightweight, surprisingly, and feels premium. It also is very comfortable in my ears and I had no issues wearing these for long periods of time due to the nice shell design, weight, and comfort. The cable is also wonderful to use.

In fact, the silk-braided cable is housed in a nice soft rubbery-sheath that is easy to move around, unwind, and doesn't tangle easily. It terminates in an L-connector of both 3.5mm and 4.4mm varieties. Yes, there are two cables included in the box. The connectors of choice for the Sony IER-M9 is mmcx, it fits in a recessed opening on the M9 shell.

In addition to the cables, the M9 comes with 13 sets of tips to choose from, as well as a carry case, and a series of other accessories. The unboxing for the M9 is quite nice, though still lacks to the drawer box approach of the IER-Z1R.

Sound Impressions
The Sony IER-M9 was mostly paired directly with my Sony NW-ZX507 digital audio player for the majority of the time I used it for this review. I also did try it alongside the Topping A90/Schitt Bifrost 2 combination, and an iPhone 5S. The Sony-Sony pairing is a popular one in the community and I've seen a lot of impressions of the M9 paired with the 507, so I was excited to see how these aligned with my own thoughts.

As general blanket statement, I found the Sony IER-M9 to have a warm, enjoyable and extremely coherent signature with outstanding mid-range and and generally laid-back and almost boring sound signature. I use the term "boring", not necessarily in a negative way. It's just an inoffensive sound signature that doesn't have any stand-out feature in its tonality/timbre that makes it either wrong, colored, or the like. I wouldn't necessarily call the IER-M9 reference tuning, as I do find it a little warmer and a little dark, but not overly colored.

Let's start a little differently this time that my normal reviews. I find the M9's coherency outstanding. The multi-driver setup seems to be well designed and doesn't show any disjointed sound across the board. Add to that the really strong resolution, and it seems like Sony knows a thing or two about how to make a good sounding cross-over setup and maximizing each driver's potential.

In the same sense, this is the same experience I found with the Hidition Viento in both the universal and the custom versions. Like the M9, it also featured great coherency and good resolution despite having less drivers than other models which tout tons of drivers. More does not always mean better.

To go on further with the comparison to the Viento-B, I find that both share a lot of similarities. The M9 does have 1 additional BA driver, but both are priced similarly now, and have outstanding mid-ranges where everything just sounds accurate and reproduced well. They both do lack some of the resonance and natural decay that comes inherently sometimes with the use of a standard balanced armature driver, but that's fine for their use cases.

Where I do find that they differ a little bit is in the tuning. The Viento is more reference neutral to me, and when compared to the IER-M9, the Viento has a more focused upper mid-range and even treble region, that may sound a little bright and lean compared to the M9. The M9's additional warmer lower-midrange also adds more body to the sound, and one can't really go wrong with either of these for a solid multi-BA setup under $1K. It's more about picking your tonal preferences.

Okay, I skipped a bit from my normal routine, and now I not only spoiled how I feel about the M9, but also how I compared it to what I consider it's biggest competitor in it's price class. Let's move forward with some music discussion.

I found the M9 to really go well with singer-songwriter type music. I listened to a lot of James Taylor with the M9, and really enjoyed how it presented the softer acoustic guitar songs of the famous musician. The bowed bass guitar on "Fire and Ice" has a nice amount of rumble can be pictured just slightly behind the rest of the instruments in this track, lying a little further back in the scene with its soft growl. The guitars are just over to the left of my hearing, and Taylor's voice is dead center, perhaps a slight bit to the right. The effortless vocals are shown in all their greatness with the M9, and the warm body really helps give his tender vocals in this track some character.

I didn't talk a lot about imaging characteristics a lot until just now, and I do think overall that the M9 excels in this area. It has a nice soundstage that isn't exactly wide or super deep, but it's a good playing field that's above average width and in the upper tier in terms of depth. This allows instruments to sound well separated and it makes the M9 sound open and free of chaos in the most chaotic tracks like Daft Punk's Contact.

The entire lead-up to the finale of this track sounds very detailed and intricate on the M9. The kick bass hits with some authority even if it does not have the slam and decay of typical dynamic driver like it's older sibling, the IER-Z1R. The cymbal crashes sound accurate but not over-done and this constant beating can sometimes be fatiguing on many headphones and in-ears. Again, what is most impressive on the M9 is how effortless it handles the battlefield of this track, with instruments smashing in all directions as it leads to its final build-up and closure. There's no muddiness, no meshing of sounds, and no blunted sounds. Everything comes in well-defined and clean.

My current addiction drug is Tingvall Trio, and specifically their "In Concert" live album. I'm finding myself craving the track, "Movie," for it's sweeping piano melodies, and constant snare drum attack, and heavy bass notes that keep everything gelled together. I normally enjoy this type of music with my Viento and Hifiman Arya, both more reference and neutral-bright signatures. But the added bass warmth of the IER-M9 does give the low end a little more body and power to it. The slightly darker treble helps give these types of songs a nice romantic-type sound approach that is easy to enjoy for long periods of time, while not losing any of the soundscape.

I've said a lot of praising remarks to the IER-M9 and the question to be asked is, where does it rank and will you buy it?

The second question is a quick, "no." And it's not because I don't like it. I do like it, but I don't find it different enough than what I own now to make it a purchase. I already have the Hidition Viento-B, and its tuned closer to my neutral preference target, and I prefer a little more air, and a little more upper-mid range than what the IER-M9 provides, but in many ways, I could go either set, as a stand-alone multi-BA IEM to use .

As far as the first question, I think the M9 stands on and near the top of the IEM playing field. It's not the best multi-BA IEM, as I still believe that title goes to either the qdc Anole VX or the 64 Audio U12t, but it's that small tier below where the Hidition Viento and Vision Ears VE8 reside for me.

At $1000, I think this is a nice buy that comes with a great accessory package and a great build. It has a few minor flaws, that are more preference things than anything else, but that's typical in this price category where preferences matter more. Good work Sony.
Excellent review, the comparisons with other IEMs and the description of how they sound with specific tracks are clear, understandable and valuable. Having owned the M9 for half a year I find the description very accurate. Really well done.

Watermelon Boi

100+ Head-Fier
Pros: Monitoring signature yet beautiful and engaging sound
- Huge set of accessories
- Solid yet light earpieces
Cons: Bass quantity may not enough if looking for strong bass rumbles

Sony IER-M9: Presenting a new way

It would be too obvious if I try to introduce Sony at this point. Sony is a worldwide electronics company and takes a significant role in the audiophile markets. There are several IEMs that come to my mind when talking about Sony. Their EX-1000 was known for its wide frequency range back in the day when Hi-Res was even a thing. The XBA-Z5, Sony's previous flagship model that has been receiving positive feedbacks. And of course, the twin models - N3AP and N3BP were great as well.

Sony has been quiet with their flagship or premium products since their XBA-Z5, until recently they came up with their new premium line up - featuring IER-M7, IER-M9, and IER-Z1R. Each model houses 4BA, 5BA, and 1BA+2DD. In this review, we will be covering the most common and popular model from the family, the IER-M9.



Sony stepped up their game with the packaging for these new flagship line-ups. Inside the box includes a generous amount of accessories along with the earphone. It comes with 6 pairs of Triple Comfort eartips, 7 pairs of Hybrid eartips, a hard case, 2 stock cables (3.5mm/4.4mm), a hard case, a cable strap, and some paperwork. Solely the eartips cost a lot if you try to buy them separately, so I appreciate the generosity.


Variety of eartips: Sony triple comfort / Sony hybrid

The two different stock tips are called Sony hybrid (right) and Sony triple comfort (left). The hybrids tend to snug into the canals close and tight, bringing the sound closer as well as increasing the clarity. The triple comfort, on the other hand, adds a little more bass and provides a similar fit of a foam tip while keeping the clarity. Both types work out nicely with the earphone and recommended give both a try before moving onto aftermarket eartips.


Earpieces - Design

The outer surface is finished with matt black and glossy carbon for the faceplates. Looking simple and premium at the same time. The inner sides are all round-shaped and provide a comfortable fit. One interesting thing is that these do not particularly cause canal pressure while inserting although it does not have any vents either. The shells are made of magnesium alloy, but the surface is finished with a skin-friendly coating which eliminates any metallic feeling to the touch. The earpieces are light, scratch-resistant, and durable.


Earpieces - The specs

IER-M9 sports 5BA drivers per side with 1 low, 2 mids, and 2 highs. All drivers are custom built as well as the soldering materials for the crossovers. Sony claims that they have applied film capacitors instead of ordinary ceramic capacitors, leading to a 90% reduction in distortion.

Another noticeable feature is the structural difference from ordinary BA drivers. For the IER series, the metal structure that vibrates inside the BA drivers are designed to have a T-shaped rather than the original U-shaped, once again reducing the distortion. On top of that, the 2BA tweeters are applied with an additional metal alloy diaphragm and SPC wires used for the inner coil. Finally, the entire set of BA drivers are surrounded by a magnesium alloy structure with gold plated sound tubes, preventing distorting vibrations.



The two stock mmcx cables are each terminated with 3.5mm and 4.4mm jacks. The cables are made of silver-plated OFC applied with silk-weaved insulations. These cables are very smooth and barely make any microphonics even when I roughly move around. The MMCX connectors on the cables look slightly different than the usual ones, but it works completely fine with other MMCX IEMs and vice versa.


Sound impressions - Bass

First off the bat, IER-M9 does a great job of controlling the reverbs. The reverbs are clear, precise, and never get out of hands. IER-M9 presents a slightly W-shaped signature, having an adequate amount of quantity distributed throughout its frequency range. Nothing feels overdone or unbalanced while sounding rich and plentiful.

M9 brings out a decent amount of ultra-lows and mid-lows. Having them clearly presented, IER-M9's bass reproduction feels very stable, moist, and non-metallic. The bass sports a neutral thickness that punches fast, then clearly decays without getting vague in resolution. Overall the bass feels accurate and rich enough for a monitoring IEM, which never gets overpowering in quantity. I would say the lows are boosted for just about 30% from flat, showing a bass quantity that would normally follow up with a slightly v-shaped IEM.


Sound impressions - Mids

Mids show neutral tonality and it slightly takes a step forward from the lows and highs. It gives me the impression that the five drivers inside IER-M9 seem to be perfectly connected to each other as they provide very consistent and wholesome vocals. There are no signs of phase distortions yet IER-M9 still portrays a bit of 3D effect to the sound, naturally imitating a live stage environment.

Vocals also feel to be neutral in thickness which makes it equally ideal for both male and female artists. Peaks and sibilances are perfectly controlled and the sound is kept to be flowing as stable as possible. The surface is smooth, crisp, and just as the bass did, it does not get metallic in texture. Good move from Sony that they have omitted the metallic characteristics from the sound without degrading the clarity, as it is crucial for monitoring IEMs to bring out as many micro details while keeping the sound comfortable and neutral. It also works out very well with various genres and vocal types which is another important part of making a good monitoring IEM.


Sound impressions - Highs, etc.

Trebles take a gentle approach and show lesser quantity than lows and mids, but that, of course, does not mean IER-M9 compromises in the details. The splashes and airiness on the highs are kept vivid and high in resolution. Well, IER-M7 takes a step further in treble clarity and aggressiveness but IER-M9 would be a more ideal choice for diving into the details without getting fatigued (as well as achieving better bass performance). Trebles from IER-M9 sports an organic, lush texture with smooth edges, making it easily enjoyable for most users.

Staging is on the larger side and spreads out nicely towards the x,y, and z-axis. I would not say this is the largest headroom I have experienced from an IEM, but along with 64 Audio Tia Fourté, IER-M9 brings out one of the best stagings in terms of accuracy and imitating a live stage set. While pumping out a rich and full sound, the staging does not get loosen or flabby, thoroughly respecting its accurate nature.


Eartips / cable matching

Sony always recommends 4.4mm termination and the same goes for the IER-M9. Compared to the stock 3.5mm cable, the 4.4mm one slightly thickens the sound with enhanced ultra-lows and headroom size. Mids gain a little more force and get tighter as well. IER-M9 matches pretty well with different cables and eartips. For cables, I have found silver-based ones to match nicely - Effect Audio Eros II or Acoustune ARC32 for example. These make the upper frequencies to shine even more, but it's really up to your personal taste as well as the eartips. JVC Spiral Dots, Spinfit, Triple Comfort, Hybrid, and others all matched nicely with IER-M9.



Most monitoring IEMs tend to have flat-surfaced vocals, though Sony suggests a different way - to recreate a realistic, lively headroom inside the listener's head. Although IER-M9 has good musicality with a slight w-shaped signature, it hasn't neglected its identity as a monitoring in-ear and presents a sound of "how it is really supposed to be". This makes it possible for professionals users to have better communion with the instruments as well as satisfying average users to enjoy their music. I have no doubt calling this IEM to be an outstanding all-rounder.


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Sony IER-M9 has been purchased by myself.
I am not affiliated with Sony and none of my words were modded or asked to be changed.


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Build Quality, Fit, Comfort and Isolation

Aesthetics (8.5/10): Matte Black shells, decorated with a carbon-fibre faceplate. A classic look, for sure, yet still awfully handsome to look at.

Build Quality (9/10): The housing of the M9 is made with Magnesium Alloy. I can’t say I’ve much experience with the material, but they feel sturdy to the touch. The MMCX connectors are made such that they do not rotate, always a plus in my books for longevity. Included cables are resilient yet fairly supple, and are tangle-proof. All in all, not quite glorious Nippon steel, but fantastic in their own right.

Fit and Comfort (9.5/10): Yes, while you might not think these Frankenstein-looking housings might fit well, they’re actually insanely comfortable and ergonomic to wear. The housings contour to my ears wonderfully, and never feel like they’re in danger of falling out. I could and have worn them for hours at a time without fatigue.

Isolation (9/10): As a general rule, if they fit well, they’ll likely isolate well. The norm, not the exception, the M9 blocks out a substantial amount of noise for your busy commutes on the Subway.


Bass (8.75/10): During my initial audition with the IER-M9, my expectations regarding the lower frequencies were not set very high – the M9, after all, sports solely Balanced Armature drivers which are often not considered optimal for the reproduction of bass notes compared to traditional Dynamic Drivers. Upon firing up my usual test tracks, however, it was quickly apparent that I had underestimated these little monitors.

The texture, decay and weight of the bass produced by the M9 is eerily similar to that of a DD, high praise for Sony’s in-house made balanced armature drivers. A general weakness of BA Bass is its propensity to sound thin and artificial, but the M9 reveals none of that. The slight bass boost in both the sub and midbass regions raises the “fun” factor, while still exercising excellent restraint. Bass is always exceptionally clean, tight and agile, highlighted by demanding drum-heavy tracks like Muse’s “Neutron Star Collision”.

Sub-bass extension is also fantastic, reaching all the way down to the lowest registers, considerably unique also in its ability to make it “felt” rather than “heard” compared to other BA setups. The rumble did, however, leave more to be desired, lacking the grunt and texture the Z1R can bring. All in all however, it’s stellar bass from the M9.

Midrange (9/10): One of the more frequently levied criticisms of the M9 is that it can sound “boring”, and this sentiment likely stems from the M9’s midrange presentation. It’s without significant peaks, neutral sounding and just ever slightly recessed in terms of stage presentation. The amalgamation of these factors ultimately contributes to bringing about the aforementioned impression many get with the M9.

The midrange however is still very much excellent, with the former mostly an issue regarding personal preferences. I do find myself clamouring for greater midrange presence at times, but objectively, the midrange of the M9 is supremely capable. It boasts fantastic clarity and detail, though perhaps just a fraction behind resolution kings like the 64Audio U12t or the Anole VX, given its greater emphasis on smoothness ahead of transparency, due to the slight touch of analogue warmth present.

Male vocals are some of the best I’ve heard on M9, perfectly conveying the velvety, rich texture of vocals such as Frank Sinatra’s and Andrea Bocelli’s like few monitors on the market can. While their female counterparts do still sound airy and natural, the M9 lacks the sparkle and brightness in the upper midrange register to really make singers like Adele stand out.


Treble (8.75/10): The lower treble on the M9 is exceptionally tuned, with sufficient sparkle to make cymbals and hi-hats shimmer and shine, on tracks like the Jackson Five’s “Want You Back”, detailed with natural decay. Far from what would be considered an intense listen though, it retains the smoothness characteristic of the M9’s sonic signature. Upper treble on the other hand has been tuned down a notch, as instruments like Trumpets on classic Jazz Standards such as “LOVE” or “Autumn Leaves” sounding neutered and unexciting, albeit still with good resolution and articulation. In the same vein, extension is unimpressive, with roll-off evident in the highest registers, once again illustrating the M9’s predisposition to favour a relaxing and non-fatiguing listen over exhibiting sheer technicalities.

Soundstage, Imaging, Separation and Timbre (8.75/10): Even against the backdrop of the prior praise I’ve lavished, the imaging and separation capabilities of the M9 are by far their most outstanding quality. It isn’t hyperbole to say that they’re likely the best I’ve had the pleasure of listening to in that regard. While the stage of the M9 is just slightly wider than average, and its depth relatively unimpressive, the sense of space created by sheer imaging and separation ability will floor you at times, especially in genres like Jazz (Count Basie for example), or live recordings. It’s an experience like no other, and therein lies the “wow” factor of the M9. The M9 also avoids most of the timbre issues full BA setups can have, possessing sufficient weight and decay to its sound. They’re great and generally a non-issue, unless you’re overtly nitpicky or anal about it

As if it were ever in doubt over the course of the review, the Sony IER-M9 gets an easy recommendation from me for those in the market for a warm-neutral type sound signature. For those who want something non-fatiguing to listen to, yet still brimming with technical ability, the M9 checks all the boxes. And you get to unbox a high end Sony product. Furthermore, they’re relatively inexpensive compared to majority of the market in the TOTL department. Did I also mention you get to unbox a high-end Sony product?

All hail our Japanese overlords.


New Head-Fier
Pros: Superb imaging, clarity, details
Strong bass (for a BA)
Great for the price point
Cons: Cable hanger is stiff
Some may think bass is too strong
In August 2018, Sony announced 3 new IEMs: the IER-M7, IER-M9, and the IER-Z1R. The IER-M7 is 4BA, retailing at S$799, the IER-M7 is 5BA, retailing at S$1,599, and the IER-Z1R is a hybrid – 2DD 1 BA retailing at S$2,299. While I’ve listened to all three, this review will be primarily focused on the M9. I’ve spent around a week or so listening to them extensively on different sources, and will explain further later on.

Drivers and Specifications
The IER-M9 is a “closed, penta balanced armature” IEM. Here are the technical specifications:
Driver Unit: 5 BA, Magnesium Alloy Super Tweeter
Impedance: 20ohms(at 1kHz)
Frequency Response: 5Hz-4000Hz
Weight: 11g
Sensitivity: 103dB/mW

I feel a need to briefly mention that these are not easily driven – quite a bit of power is needed.

Packaging & Accessories

The IER-M9 comes in a not-so-small package, including 6 pairs of Triple-Comfort earbuds(L to SS), 7 pairs of Hybrid silicon rubber earbuds (from LL to SS), a cleaning cloth, a 4.4mm balanced cable, a 3.5mm cable, a carrying case and of course the IEMs themselves. These are packaged and presented very well. The carrying case is fashionable, but not something that I would bring around everywhere.

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Build Quality and Comfort

The IER-M9 is encased in a light but durable outer casing of a magnesium alloy with a carbon fibre plate – a nice touch. The IEM itself features a pre-formed ear hanger with very strong memory, something that may appeal to some but not to others – I found that the hanger was a little bit large for my ears, but not something that would cause discomfort by any means. The MMCX connector is slightly recessed, meaning that you would not be able to attach any other cables unless you have the proprietary connector. The M9 sits snugly in my ears, although there are times that I have felt that it is a touch too big – again nothing to write home about. The isolation and fit is also great, it forms a very good seal to my ears.

With the M7 and M9, Sony has really stepped up its game in the design and comfort categories – in comparison with the MDR-EX1000 and the XBA-Z5, the M7 and M9 look and feel amazing - no more of that odd protruding bits in your ear.


As stated above, the M9 comes with 2 MMCX cable options, terminating in 3.5mm and 4.4mm balanced. The cables are almost identical apart from the termination and are silver-coated oxygen-free copper cables. The plug is an L-shaped non-magnetic gold-plated stereo plug. I find the cables to be of fairly high quality, they are long and rather sturdy, yet not too heavy. That said, the Y-split and the splitter above could be potentially larger. The M9 is designed to be worn over ear, and there is little to no microphonics at all when moving around with the cable. There is just a small worry that the wire is sheathed in a rubbery material that is just slightly sticky out of the box – hopefully this will not be exacerbated by heat and humidity.


Before I begin on this section, let me attempt to provide some context – my audio journey has been as such – Vsonic GR07 à Etymotic ER4XR and Massdrop Plus à IER-M9. I’ve spent a lot of time over the past week listening to these gems. Along the way, I’ve listened to a good many of the more highly-rated options on the market, and will be using some of them as select comparisons in this review: Sony MDR-EX1000 (coming soon), Hyla CE-5 and Campfire Audio Andromeda. I find these two IEMs to be the closest in terms of comparison.

Listening preferences – My listening consists primarily of Classical music, both of chamber and orchestral natures. I also listen to a fair amount of Mandopop and some Jazz, and my preferred sound signature being the ever-elusive “perfect neutral”. For this review, I’ve listened to the M9 and other IEMs on the following sources: iBasso DX200, Sony WM-ZX300, Fiio X3ii, Samsung S7 edge.

The first thing that stood out to me when I heard the M9 in the Sony store when trying it for the first time was the coherence and detail retrieval. I find the M9 to have a very natural and coherent sound which still providing a great deal of detail. The M9 can be described to be slightly warm, with a bass boost and some treble shine. While the staging is not extraordinarily expansive, it is both sufficiently wide and deep, and separation and imaging is top notch.


The M9 boasts a quicker and punchier bass response in comparison with most other BA IEMs. Some may even say that the bass response is slightly overexaggerated – I could sometimes feel the bass beating against my eardrums. The quality of the bass tends to be a bit direct, so it will hit you hard if the track is right. The boost here comes in the subbass, the midbass areas do not feel quite as overpowering. For me, the quantity of bass is just slightly too much, but that is coming from someone whose focus is primarily on Classical music. I feel that the bass would be at least satisfying for most.


The best way to explain the mids of the M9 would be that it is unoffensive – one would not overly notice the quantity, yet it is not missing, at a quantity that to me is just nice. There really isn’t much to write about this – it just does its job well.


The treble of the M9 is what I would classify as accurate and extended in a way that is incredibly precise. Piano tracks come out with crystal clarity, Stacey Kent sounds oh so sweet. This is an incredibly addictive sound – the presentation of the treble is so clean. Oh did I mention it still sounds natural? I find that strings in particular sound good in the higher registers, it comes across very clearly, without being shouty by any means.

Imaging and tonality

To me, this is the strongest suit of the M9 – it is fast, accurate and clean, all the while without being in your face. The M9 deals with instruments very well, be in the congested Mahlerian works, or in the more technically challenging jazz tracks. Drums come out tight and clean, and there is a very nice sheen to the cymbals. Plucked instruments – harps and double bass pizzicatos are delightful. I find the M9 to perform particularly well for orchestral and jazz tracks.

Select Comparisons (prices at Singapore MSRP)

Campfire Audio Andromeda (S$1,500)

The Andromeda has clearer spacing in general for any tracks that are less congested (Jazz, etc.), but the imaging of the M9 stands out when dealing with more congested tracks (like full orchestra). The bass response of the Andromeda is slower and less punchy, with a smaller dynamic range than the M9. This is something solved in part by using the Acoustune ARC II cable, which trades some clarity and air for quicker bass response.

I would venture out on a limb to suggest that the Andromeda does the treble range cleaner than the M9, this is probably due to the Andromeda having more space and air than the M9 – this however is a purely personal opinion.

In general, I find the M9 to have a more natural sound and a better tonality than the Andromeda, which as many have raised tend to sound unnatural. If you prefer better bass response and are willing to trade out on some of the “air”, then the M9 would be better for you.

Hyla CE-5 (S$1,600)

The Hyla has a more V-shaped sound in comparison to the M9, with a more noticeable dip in response in the midrange. What the Hyla does better than anything else at this range is bass. While the quantity of the bass for M9 and Hyla is somewhat similar, the quality and tonality of the bass is a fair bit more convincing on the Hyla – it does not quite hit as hard, but with a nuance and well-managed impact that is much more pleasing to the ear. I must note that the Hyla has a very coloured sound – so if you are looking for more “reference”, this would not be for you. The Hyla in general has a more fun tuning as compared to the M9, though is not nearly as technically proficient in terms of imaging and clarity.

Sony MDR-EX1000 (Out of production)

I have yet to be able to do this comparison, so I will update this later.

Etymotic ER4XR (S$499)

It is perhaps slightly unfair to compare the ER4 and the MD+ in the same review as the M9, but I will do so anyway since it was the upgrade path for myself.

The ER4XR has a much more neutral and flat tone, unlike the M9 which is a fair bit more coloured. In terms of technical ability, it provides slightly less in details, but does not quite present them as well. The sound of the ER4 is immensely analytical, even cold, which could make for difficult listening, unlike the M9 which you can listen to for hours.

Massdrop Plus (~S$400)

The MD+ has a fun signature, that is a fair bit more colored than the ER4, sacrificing details and treble extension for more well-managed bass response. What is immediately clear is that the technical ability of the MD+ is nowhere near the M9 (obviously it is an unfair comparison), where it sounds muddy by comparison. Details do not come out as cleanly, and while the midrange performs admirably, there is an obvious roll-off in the treble range that could be a major turn-off for some people.


The IER-M9 is an incredibly technically proficient IEM that does very little wrong, beating out many of the competition at this price point (including CIEMs). It is presented in a very professional packaging, and the sound is excellent. It handles almost all genres with easy, aided by solid performances across the board, with fast and quick response, stellar imaging and plenty of details. While the staging could perhaps be wider, it does not sound intimate, and the boost to the bass is very commendable for BAs, while I find the treble extension to be natural and unforced. At the price of S$1,599, there is little to complain about for this remarkable IEM, which I have absolutely no regrets buying.


The tracks I used for this review are as follows:

Franck Violin Sonata in A Major, 4th Mvt, Kyung Wha Chung
Mendelssohn Octet 4th Mvt, Academy of St. Martin in the Fields
Brahms Piano Trio No.1, 1st Mvt, Maria Joao Pires, Augustin Dumay, Jian Wang
Prokofiev Violin Concert No.2, 1st Mvt, Arabella Steinbacher
Tin Sogno Di Volare (“The Dream of Flight”)(Civilization 6 theme)
Holst The Planets, IV. Jupiter, London Philharmonic, Boult
Mahler Symphony No.2 “Resurrection”, 5th Mvt, Lucerne Festival Orchestra, Abbado
Prokofiev Symphony No. 1 “Classical” 4th Mvt, London Symphony Orchestra, Gergiev
Prokofiev Piano Sonata No.7, 1st Mvt, Pollini
Giacchino The Incredits from “The Incredibles”
G.E.M 泡沫
Jay Chou 听见下雨的声音
Davichi Forgetting You
Suzy, Baekhyun Dream
Girls Next Door Deep Blue Eyes
Stacey Kent You’ve Got a Friend
Anne Bisson Do What You Please
Frank Sinatra Fly Me To The Moon
Fall Out Boy Thanks for the Mmrs


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is there any difference when using triple comfort tips vs hybrid silicone in this case?
I few the triple comfort gives a bit more bass extension and details, but only if the seal is perfect any leak the bass will drop considerable for me. Even though I really preferred the Bass with the TC, I can't handle the annoyance of adjusting the IEM every 5 min. to keep the seal. Interestingly the TC on my Andromeda S and the fit is perfect. But I still love the sound of the Silicon Tips.
Yeah, the smooth foam kinda push out after a few min. I do notice after a few days wearing, they don't move out as much anymore. Maybe out of the box, they're too smooth and stiff?