Sony IER-M9 In-ear Monitor Headphones

Sony ier m9 is a legendary kilo-buck iem. It doesn't need any introduction.

All the testing were done using

• Ibasso DX170
• 4.4mm cable
• Divinus velvet , Dunu candy and S&S tips.

Build and Design:
The body is built with magnesium alloy and the faceplate of the iem has carbon fiber like pattern. The nozzle is on the thinner side, not to too long as well. There is foam padding inside the nozzle which works both as tunning filter and absorbing humidity.
Over all the build is solid. It is built to last long.

Specifications :

• 5 sony custom BA drivers (Magnesium diaphragm )
• MMCX connection
• Silver coated copper cable (4.4mm and 3.5mm)
• 

Sound:
First of all thanks to magnesium diaphragm it doesn't feel like BA. The decay is slower than traditional BA iems.
Bass: The bass has a very quality and textured to it. Not like dynamic drivers, but its there. The bass lacks the body and authority. The depth of the bass is missing. (woomph sound)
Sub Bass : I haven't heard sub bass like this in any iem, I have tried so far. It is creamy, textured. Like, if you listen to the song Lovin on Me you will feel those sub bass notes.
Treble : Treble is the main attraction of this iem. One word "Smooth". It has a very good treble extension. You can listen to it hours after hour but it won't be fatiguing at all.

It has a very wide sound stage, very good imaging. Instruments play separately in their positions. It wraps around your head, creating holographic image. All the details are there but they won't slap on your face and make you overwhelmed. Rather the instruments are being played harmoniously, You will be able to hear them clearly if you pay attention. Lets say you are thinking about something, the instruments won't bother you. The moment you are paying attention and looking for that bass guitar slide, its there!
Both male and female vocals sound excellent. Vocals are forward. Immersive would be an appropriate word I suppose.

Verdict :
We sometimes chase after technicalities and details. But for longer session it can be double edge sword. Sony IER M9 sits in a perfect position where its not overwhelming.
If it had punch and depth of bass like dynamic driver it would have been cherry on top. Aside from knit picking, it is the Legend.

The IER-M9 is a 5-BA configuration IEM produced by Sony, and it has been on the market for quite some time. I've owned a personal unit for several years, and here are my sound impressions:



Fit and Comfort:
For most of my listening, I've used the Silicon Hybrid tips that come with the packaging. The fit is crucial for the listening experience, as the IEM must conform well to your ear cavity shape and feel snug. It should be a deep fit, so choosing the right tips is essential; otherwise, you might perceive the IEM as too dark-sounding, when it isn't. Once you have the right fit, the M9 is, in my opinion, one of the most comfortable universal IEMs I've tried.


Bass:
The bass doesn't sound like typical Balanced Armature (BA) drivers, but it also lacks the physicality of a Dynamic Driver (DD). What you do get is a decent sub-bass and nice mid-bass warmth, giving it an enveloping feel. However, the level of warmth might not appeal to everyone, especially those who primarily listen to genres like hip-hop or EDM. If you're looking for clean bass with good texture, there are other IEMs on the market, such as the Symphonium Helios.


Mids:
This is one of the more interesting aspects of this IEM. If you've seen the graphs of the IER-M9, you'll notice that its tuning differs from more traditional Harman-tuned IEMs. Despite not being a vocal-centric IEM, it represents vocals very well. The presentation of vocals is somewhat off to the side, as if you're listening to a performance through a screen behind you. The 7th Acoustic Supernova does outperform the M9 in the vocals department.


Treble:
The treble can make or break the sound signature of a warm-sounding IEM. When not executed correctly, it can lead to a dull sound. Fortunately, the M9 has excellent treble extension. None of the treble frequencies sound too peaky to me, and they are well-represented in the air region. The sparkle and cymbal crashes are just right, not piercing or dry. In fact, I use the M9's treble region as my baseline when listening to other IEMs.


Tuning and Technicalities
The M9 has really good timbre and coherency, and despite its warmth, it exhibits pretty good detail retrieval. However, it's not the most dynamic sounding and has rather slow transients. While it does not come off as the most exciting IEM, it still maintains a balanced tuning and can be treated as a reference.

The M9 has a truly impressive imaging capability. It creates a spherical presentation of the music around you, a performance that, in my opinion, is on par with some headphones. While it can be driven off an Apple dongle, it truly shines with more power. The M9 scales remarkably well with source improvements. I've thoroughly enjoyed listening to it through the VMV D1se and the Singxer S-A1 chain. Does it have technicalities that can beat most IEMs priced above it? No, but it's very good for the price range of just under a kilobuck.


Conclusion
Sony, as a brand, is highly trusted in the audiophile community, and they have made a nice addition to this niche hobby with the IER-M9. I've owned my M9 since 2020, and despite some of its faults, it remains a mainstay in my possession. If you enjoy a plain and relaxing evening with some nice jazz, I recommend trying the M9. I believe you will like them.

almost 5 years since its release yet still it remains special for $1000 iem
one of my favorite iem beside sennheiser ie600

build like a tank using magnesium housing & very smooth and non microphonic cable, it might look simple but when i hold it and use it, it definitely feels like TOTL quality

ergonomics is very very subjective but for my ears, using its ML size sony hybrid tips, they fit like a glove for my ears
the only thing preventing me for using them for too long is the lack of any pressure release, after around 2-3 hours i need to take em off for a while to relieve my ears from the pressure buildup due to how sealed they are


sound wise i could categorize them as neutral warm, with very special imaging capability

just a lil bit of note here, they requires power, using 3,5 mm + phone it sounds... mushy and congested, but with proper source and power, man..... they are magical

bass is thick and textured, actually it extends well to the sub bass, somehow it almost feels like dynamic driver, sometimes but because of elevated mid bass, sometimes lacks a bit of sub bass for me, but honestly they are enough and enjoyable for most of my playlist

midrange is so sweet and natural, there's an effortless warmth layer to it but for me it's a "just right" kind of warmth to make female and male voices sounds natural, sweet and romantic,
just a little note though, if you are accustomed to harman/ df neutral kind of ear gain, M9 do feel lacks elevation in ear gain area

treble is strangely unique for me, it is effortlessly extended yet far from any metallic tinge, very smooth, at some songs it does feel laidback but with a a strangely good air extension, for violins like lindsey sterling - dance of the plum sugar fairy, sounds sweet yet has a good bite for the violin energy.

so yeah unique presentation for me, at first you might thought they sound almost dark but when you really listen, it actually extends really well with good bite when needed

also as a full BA driver iem, i feel that they are one of the the most coherent sounding BA i've ever tried from top to bottom sounded complete and coherent, also timbre wise, they are somehow quite close to dd timbre presentation


now technically, again they are uniquely technical in a special way

as an overall they have this warm ish kind of sound that does make the transient a bit blunted, lacking incisive attack and dynamics, resolution wise they are not the best for the price

soundstage is very wide, especially left and right area with good depth
but the magical thing is the imaging, the capability to portray where a certain element either instrument or vocal is coming from... i don't know what kind of thing they have done but man the imaging is certainly magical for my playlist

the thing is.. i've tried (and measured some of them) TOTLs like 64's U12T, U18T, Trio, Fourte, EE Odin, VE phoenix and EXT, even Sony's own Z1R, but none of them could give me imaging like the M9 (yes those iems are objectively better in technical compared to M9 resolution, detail, 3D etc. but the imaging...... the imaging .. is different)

hearing Encanto's OST - we don't talk about bruno : every performer is dancing around my head circling front, left, and right, even i could pick some percussion playing on my upper right to upper left side, it reminds me of a multi speaker presentation from movie theater

hearing Alffy Rev's - Indonesia Wonderland & beauty of Bali : again every percussion, traditional instruments, sounds of birds chirping are playing circling around my head going up and down in a very realistic way

Greatest showman OST - from now on : during the ending session (and we will come back home and we will come back home....) the singers are singing around me, tamborine and percussion coming from my upper head, steps from below, almost feels like i can really imagine the scene in the movie

even other iem might sound more detailed and higher in resolution, but this kind of imaging i have only heard them from M9

so in the end this iem is VERY SPECIAL for me, it might be boring for some due to its lacks of dynamics but for me
everytime i hear it, it feels like i'm sitting on my couch and hearing an analogue warm speaker system that makes every music sounds amazing

currently these two are simply my favorite iems

ie600 is for fun, very dynamics and engaging
M9 is for me during calm time, and when i want to feel that special imaging

ie600 takes me on a thrilling adventure
M9 takes me back to a comfy home