Lime Ears Model X

Dobrescu George

Reviewer: AudiophileHeaven
Pros: + Good build quality, with nice aesthetics, the Lime Ears logo and the carbon plates look pretty nice in person
+ Very complete packjage, with good quality tips included in the package
+ Easy to drive, yet scales well with better sources
+ Fun sound with two possible tunings, one that is analytical and bright and one that is more fun and V-Shaped
+ Pretty good resolution, detail and dynamics
Cons: - Carrying case, while cool, is not practical
- Soundstage is best when the bass boost is turned on
- A bit of void, requires slow insertion
- Needs a good source to sound truly good
- Not the best default cable
- Neutral tuning is a bit sterile
- May be a bit large for small sized ears, situation in which the custom version is more recommended
Hot and Cold - Lime Ears Model X Universal IEMs Review

Lime Ears is a very stylish company from Poland, well versed in creating IEMs as well as CIEMs (customs), and known for having some sleek designs and friendly employees. Since Model X has a rather high price tag, of about 900 USD, Model X has to stand its ground quite well against other flagships, like Fibae Black from TheCustomArt, Campfire Atlas, and even something like Beyerdynamic Xelento, all of which are other interesting flagships Model X will be compared to.


Lime Ears has a more unique name and approach to the marketing when it comes to creating and selling IEMs and CIEMs, and although this is not unique, I'm here to remind you that if you have any fit issues, Lime Ears offers up to three refits for their CIEMS! This is quite excellent, as your CIEMs may not fit if you have large amounts of weight gain or weight loss. Furthermore, even if the impressions weren't perfect the first time, in the price of the IEMs, you get 3 refits, which is quite excellent. Another thing you need to know about Model X and Lime Ears IEMs in general is that they come with the whole range of tips and accessories, and that Lime Ears likes to provide a full service with their IEMs, making it really easy to recommend working with them and purchasing their products.

It should be noted that I have absolutely no affiliation with Lime Ears, I am not receiving any incentive for this review or to sweeten things out. This review is not sponsored nor has been paid for by Lime Ears or anyone else. I'd like to thank Lime Ears for providing the sample for this review. This review reflects my personal experience with Lime Ears Model X. Every opinion expressed is mine and I stand by it, the purpose of this review is to help those interested in Lime Ears Model X find their next music companion.

Product Link (no affiliate links)

About me


First things first, let's get the packaging out of the way:

While I just reviewed Fibae Black from TheCustomArt, and it had almost no package, Model X from Lime Ears surely sports a package you will not forget.

Starting with the case, they went with a fully customized cardboard case, inside which you can find the magic. The new original package comes with some Polish sweets so good, that I could recommend purchasing Model X just so you could get a taste of the amazing delicacies Lime Ears includes with their IEMs. Joking aside, they are really good, not the kinda sweets you usually get from the supermarket.

Furthermore, Model X comes, not only with tips, but the best of the best, Spinfit tips. I am amazed by the fact that the guys at Lime Ears, who wasn't so known before, have decided to go with the sme of the best tips in terms of comfort.

You can also find foam tips and hybrid tips in the package, but the next thing is even more impressive, Model X actually comes with a carrying case, that's a solid cylinder made of metal. I'm not even underestimating things here, the case they come with weights almost half a kilo, this is the case that will protect your IEMs even against a nuclear explosion, well, if you've been watching the beloved Chernobyl series.

The cable is single ended, but it is one of those typical custom IEM cables that is thin, yet of a very high quality.

Overall, Model X from Lime Ears really took me by surprise, I am not used to seeing something this fancy, and they totally deliver just right for their price bracket.

What to look for when purchasing a high-end In-Ear Monitor

Build Quality/Aesthetics/Fit/Comfort

Starting with the build quality, you will notice that the universal version of Model X is actually designed in such a way that is slightly different from the custom version, because the bore, or the tube that holds the tip, is made of metal, and has 3 tubes inside. We're not talking about just a custom made universal, it looks like Lime Ears decided to make a unique universal IEM.

The outer shell is made of acrylic, like most custom IEMs that are universal, but you will notice a beautiful overall design with Lime Ears's logo and the carbon texture on the outer shell. The IEMs are marked left and right, and so are the cables, as they rely on the 2-Pin connector. In my future review of the Dunu Hulk Cable, you will notice that Model X pairs flawlessly with other cables that are based on the 2-Pin connector.

The overall aesthetics of Model X are simply outstanding, truly worthy of a flagship IEM priced at 900 USD, they are simply sleek, beautiful, and the vibrant Lime Ears Logos complete the picture, although you can customise the faceplates, or at least that is an option for the custom version.

Now, the comfort is okay, but you need to keep in mind that both the IEMs and the bores are on the slightly large side, and the overall IEM sits a bit out of your ears while you're wearing them. Another thing to keep in mind is that the cable has a rigid ear guide, so it will sit in place after you adjust it, but not everyone has the same luck with solid ear guides as they do with flexible ones.

There are 4 BA drivers inside Model X, but the main reason they are a bit on the large side is that Lime Ears wanted to have a proper acoustic room inside the IEM, so you will be able to enjoy a more natural sound. On the note of the tech used inside Model X, Lime Ears has implemented something called "VariBore" and something called "Passive acoustic resonator". Both of those technologies are aimed at giving the bores a specific size, length, and volume to control the resonances inside the IEM better, and to provide a sound that is both natural, and which doesn't have unwanted reflections coming from the bore.

There is a bit of void, but you don't get bad void, and you get no driver flex with Model X. They are somewhat easy to drive, although they do pick some hiss from hissy sources. Most hiss is not audible when playing music anyways, so that shouldn't be an issue, they are not as hissy as Campfire Atlas for example.

Lime Ears Model X provides a huge amount of passive noise isolation, so you don't have to worry about owning the universal version, they will isolate so well, you will be able to use them on stage, if you'll decide to perform, and if you'll want a universal IEM rather than a Custom One.

Overall, Lime Ears have designed an outstanding IEM that looks and feels good, proper for this price range.

Sound Quality

The title may give it away, but those IEMs literally sound hot and cold. There is a little switch on the outer surface of each IEM, and that one is used to either engage or disengage a bass boost that's quite serious, of about 8dB, from 800 Hz and below.

This means that there are two very different tunings you can hear Model X in, either the hot or the cold tuning, thing which I also mention in my short Youtube review of Model X.

The cold tuning is bright, with the treble quantity being larger than the bass quantity, but with such a clarity and detail that you'll immediately be amazed by the sheer amount of resolution Model X has. The midrange is slightly dipped in this configuration, so you get a very moderately U shaped signature, where the dip in the midrange is a bit similar to IE800's dip in the midrange. The treble is pretty peppy and forward, with excellent details until about 9kHz. The bass is extremely fast, but neutral, with the bass boost turned off you're surely going to either enjoy it immensely because it is neutral, or you're going to reach for the bass boost switch so you get a more lush should with more substance and impact.

The thing is, even with the bass boost turned off, the depth of the bass is quite excellent, and it is a fast and impactful bass, but the amount of treble and upper midrange is higher than the amount of bass, so much, that in this neutral configuration, you are probably going to be switching the Bass Boost on, unless you were looking for a very neutral sound.

The midrange is quite sweet and musical, but at the same time it has a pretty large amount of recession, which feels somewhat similar to IE800. Funnily enough, what I appreciated back then about Ie800, is also true about Model X, they have a very juicy and textured presentation of guitars, but they aren't grainy nor fatiguing, having a very natural overall tonality for their midrange.

The treble, in this cold configuration, is pretty bright, open and sparkly. If you enjoy a really open treble, this should be for you, but please keep in mind, we're talking about amounts of treble similar to HD800, it isn't a joke, it is a pretty peppy and forward kind of treble, that all of you, treble lovers will surely enjoy. There is no grain, no harshness, and there is a ton of detail and clarity, so you surely won't be disappointed by its presentation.

The hot tuning is probably what most will be using, because now the bass has a boost of about 6-7dB until about 700 Hz. This means that you get a pretty significant bass boost, sub-bass boost, and even some lower midrange and upper bass boost. In this state, the soundstage becomes deeper, the entire sound is much more V-Shaped, there is a lot more impact to the sound, and male voices, and low timbre instruments gain a much better body and authority.

Starting with the bass, now the bass is elevated compared to the midrange. The speed of the bass feels slower now, and you can actually call it "a more natural bass" overall, but you need to keep in mind that this is a very full and impactful bass, it really fills out the entire room. The bass is enhanced up until the upper bass and lower midrange, at about 700 Hz, so you can totally feel the rumble and the depth.

The midrange also has more authority, and you can hear that male voices are deeper, fuller and more convincing of a real life performance. This doesn't work quite as well for female voices, which I tend to like a bit better with the bass boost turned off, at least for certain J-Rock and J-Pop bands, but except for their lack of presence, they are still very sweet and clear even in this configuration. Guitar presentation tends to be sweeter, more emotional and also to have more body and presence, so this configuration really compliments most music if you're not very addicted to a very neutral presentation.

The treble is much better balanced by the bass now, and the overall signature is more reminiscent of the Campfire Atlas overall tuning, this time the treble serves much better to sprinkle the entire sound and to not only give the sound sparkle, but also a good balance. I think that right now, Model X is at its best, having a really amazing overall detail, but also expression for their treble

Overall, they are pretty dynamic, especially with the bass boost engaged, and they are of a pretty high quality, especially when it comes to the overall resolution, clarity and precision, making Model X easy to recommend. If you're a fan of having two very different tunings, those surely will be a love for you.

Portable Usage

There is no one in this world who'd want anything more than Customs for portability. You simply don't have to care anymore about anything, someone wants to tell you something, nah, you simply don't hear them. You pass near a construction site, you don't hear anything. You literally can be out and about without a care in the world, being fully isolated from the outside noise.

Now, when it comes to the universal version of Model X, they are quite outstanding as well, you get a pretty solid IEM, that isolates quite a lot from the outside noise, which is fairly easy to drive, and which has just a bit of hiss, so you can use it with almost any source you have, maybe except for those that have a really high output impedance.

Since there is no data on Lime Ears's site about the impedance and the SPL of Model X, I can't really tell you either what exactly the impedance and the SPL is, but they get loud fairly similar with iBasso IT-04, which is a 16 OHM / 110 dB IEM, and they pick up hiss in a similar amount to iBasso IT-04.

When you take Lime Ears Model X on-the-go, you probably will be using the little pouch they provided rather than the large metallic case to carry them, and as much as I love that huge, heavy case, I don't think it is the most practical of carrying solutions for IEMs, especially since it doesn't really fit in a pocket and would be too heavy to be practical anyways.

Overall, Model X from Lime Ears makes an excellent portable IEM that you can take with you anywhere, and which is impressive in every possible way when it comes to their ability to block out noise, although if you really want the best isolation possible, you should consider the custom version of this beauty.


As stated at the beginning of this review, to stay in a similar price range, I have chosen Campfire Atlas, Beyerdynamic Xelento, and Fibae Black to compare Model X. Fibae Black may stand out a bit because it is less expensive, but the main reason I'm including it in the comparison list is because both IEMs are from Poland and I like how they compare to each other, even though they are from slightly different price ranges.

Lime Ears Model X vs Campfire Atlas - Starting with the build quality and comfort, I think that both are made really well, the biggest difference here being that the cable Atlas comes with is of a better quality, and that Atlas is made of metal rather than of acrylic like Model X. In terms of comfort, for me Atlas had driver flex at first, but it seems that after using them for a while, the driver flex disappeared, but I should also mention that I used Atlas both in full blown summer and in Winter. Now, Model X is the void kind of IEM, you need to insert and take them out slowly, but so is Atlas for the most part, you just want to be careful with IEMs and not force them in your ears. In terms of sound, Atlas is and Model X are quite similar in signature when Model X has the bass switch turned on, both have a very convincing bass and impact, although Atlas has a slightly better edge in terms of bass quantity, impact delivery, rumble and depth. In terms of midrange, both have a similar presentation, although here Model X is a bit sweeter, where Atlas has a slightly more specific dip in the midrange. Model X has the entire midrange recessed, so a wider dip. The treble is more peppy and forward on Model X, Atlas being slightly more smooth. This being said, Atlas extends a bit higher with a bit more detail until a higher frequency. When thinking about which one to get, you need to take into account that Atlas is an upgrade to the original sound of Model X with the bass boost turned on, especially in terms of resolution, depth, dynamics and punchiness, but Model X has also the bass boost turned off sound mode, and Model X can come in a custom version, which will be better in terms of fit and comfort than both Atlas and the Model X universal.

Lime Ears Model X vs Beyerdynamic Xelento - Xelento is one of the IEMs people are still using, even though it is not exactly new at this point. In fact, a lot of people have been expecting a Xelento upgrade from Beyerdynamic for a while now, and although nothing is officially confirmed yet, there has been talk of one recently. Now, when it comes to comfort, Xelento is much more of a shallow fit IEM, but it has driver flex. A large number of people have found Xelento to be very comfortable though, and in comparison, it is smaller and easier to fit with any size of ears, than Model X which is slightly on the larger side. The cable Xelento originally comes with is better than the cable Model X comes with. There is a Bluetooth cable for Xelento officially made by Beyerdynamic available on the market as well. Now, the sound, is actually quite different. Xelento is creamy, punchy, deep, but very very smooth in the treble, it has a very smooth and velvety treble, leaving the bass and mid to play, but hiding the treble behind. By comparison, Model X has a better treble extension and more treble detail, or at least, they are much better at revealing that detail. If you want a really smooth and creamy IEM, with nice depth, impressive bass, warm and thick sound, full presentation, but with a very very smooth treble, Xelento is still a very interesting choice, but if you want something that's more balanced across the spectrum, but is still very full and has a nice body, then Model X with the bass boost turned on makes quite an excellent choice. This being said, Model X also has a bass boost turned off sound mode, in which it is bright and neutral, so you get two signatures in one with Model X if you decide to make it your choice, and if you're curious to explore things.

Lime Ears Model X vs TheCustomArt Fibae Black - Ah, two IEMs made in Poland, by two companies that are physically quite close to each other. I know that I should probably be stacking Model X against Fibae 4, but until that gets to me, I wanted to showcase mainly that both companies make an excellent work in designing a very well made and comfortable IEM. This being said, there are differences, The Custom Art places much less emphasis on the package of their IEMs, but includes a more practical carrying case, they also managed to design an IEM that is physically smaller and which is easier to fit with a wider range of ear sizes, having the bore thinner and going deeper in your ears. Fibae Black relies on an inner sonic chamber design to do their magic, while Model X has a lot of optimisations in both the inner chamber and the bore, and especially in its sound tubes, and each technology has its advantages and strengths. Fibae Black manages to be very laid back, relaxing, smooth and easy to listen to, while Model X is exciting, has a lot of treble, they have better dynamics and are more versatile having two sonic modes. This being said, I have at least one friend who heard both and told me he will order a Fibae Black, because Fibae Black is also almost half the price of Model X, so while Model X has some advantages, Fibae Black still will have its fans and people who'll decide to go for it.

Recommended Pairings

For the pairings part of this review, because Model X is easy to drive, yet does scale with a better source, I have chosen QLS QA 361 Portable Player, FiiO M6, and Mytek Brooklyn DAC+ as the main pairings for Model X.

Lime Ears Model X + Mytek Brooklyn DAC+ - Why not start with the best pairing, I thought to myself, knowing that this is a weird move and that some people may judge me for it. Brooklyn DAC+ is a proper flagship that amazes me every single day I'm using it, and well, I'm using it almost daily as my benchmark and main Desktop Headphone DAC/AMP. The pairing between Model X and Brooklyn DAC+ is quite outstanding, both in terms of soundstage width, depth, but also in terms of dynamics and how real those little IEMs can sound. On the other hand, Model X picks a smidgen of hiss from Brooklyn DAC+, and you can notice that physically it may not be the best option, unless getting a different, maybe longer cable, for Model X. The sound is plenty detailed, has excellent dynamics, impact and depth, especially with the bass boost turned on, and has very nice revealing abilities when the bass boost is turned off.

Lime Ears Model X + FiiO M6 - FiiO M6 is one magical little device, not because it is the best sounding in the world, but because it is small, has all the streaming abilities you can desire, is very neutral and has a beautiful sound for its price range, especially when you remember that there are very few devices that sound this good at that price range. Furthermore, M6 has a smooth UI, has most of its software issues already sorted out by FiiO, and is able to power Model X properly, with little to no hiss, making it quite an outstanding pairing for Model X, if you want to have a small, portable, lightweight, yet very capable DAP to drive them quite well, especially for the price point of M6.

Lime Ears Model X + QLS QA 361 - I felt like ending this review recommended pairings, with something magical, so QLS QA 361 is the choice, this is a magical DAP, that has no streaming abilities, it simply reads your music collection from a microSD card, so you don't have to worry about anything else. The Amplifier module inside QA361 is one of the best there are, you'd be amazed by how much work went into designing it to sound the best it could. Overall, QA361 has a softer sound, that really compliments harder edged IEMs and headphones, and now, this works beautifully well with Model X, because it makes them even sweeter and slightly softer, more musical than their normal sound. The softer signature of QA361 compliments Model X both when it has the bass boost turned on or off, and QA361 feels like a really sweet match for Model X if you don't need streaming and other bells and whistles that other DAPs can provide.

Value and Conclusion

The value of Model X is undeniably good, you get not only the IEMs, but also a fancy carrying case, proper Spinfit and hybrid tips, and even foam tips, you get some of the best sweets I have tastes, as a treat, and you get a very solid IEM, with two possible tunings, one that's warm, V-shaped and fun, and one that is neutral, reference, and a bit cold and bright, leaving the best of each world to you.

Starting with the build quality and comfort, Lime Ears surely haven't missed a thing in terms of how comfy and well made they designed their IEMs to be. The aesthetics are beautiful, and that carbon face plate is pretty beautiful, with the Lime Ears logos also adding a nice touch to the overall design of their IEMs. The comfort is okay to good, depending on how large or small your ears are, but you can always get the custom version, which will mean that regardless of what your ears look like, you'll get heavenly comfort. And with Lime Ears's warranty and reshell options, of having the IEMs re-fitted 3 times during their lifetime, you really don't have to worry about getting your first custom IEM, they will still fit regardless of what changes happen in your life, and if they won't, Lime Ears will be there to support you.

The sound has two sides, one that is bright, analytical, sparkly, and which compliments female voices, and detail, and one side that is V-shaped, is fun to listen to, and compliments everything, form guitars, male vocals, and even pianos, including large organ pianos. All of this is at the flick of a button on the outer IEM shell, so you don't have to worry that you have to replace filters or such, the Bass Boost is really easy to reach and engage.

I have to add Model X to Audiophile-Heaven's Hall Of Fame, because it is a very interesting IEM, with two possible tunings that will surely bring a lot of fun if you decide to go for it, making it a good entry for our list of the best products we've ever tested.

At the end of this review, if you're looking for a IEM, or a CIEM, one that can do two signatures, both be analytical, sparkly and happy with the treble, and a signature that is more fun, V-shaped, and which feels both deep, wide, dynamic and punchy, if you want to have the option of getting up to 3 re-fits, and if you want to get one of the best overall packages, and taste the sweet taste of Polish candy, you should totally consider Lime Ears Model X, it is a unique IEM with a lot going on for it.

Product Link (no affiliate links)

Full Playlist used for this review

While we listened to considerably more songs than those named in this playlist, those are excellent for identifying certain aspects of the sound, like PRaT, Texturization, Detail, Resolution, Dynamics, Impact, and overall tonality. We recommend trying most of the songs from this playlist, especially if you're searching for new most, most of them being rather catchy.

Tidal Playlist

Song List

Bats - Gamma Ray Burst: Second Date
Eskimo Callboy - Frances
Incubus - Summer Romance
Electric Six - Dager! High Voltage
Kishida Cult - High School Of The Dead
Dimmu Borgir - Dimmu Borgir
Breaking Benjamin - I Will Not Bow
Thousand Foot Krutch - The Flame In All Of Us
Gorillaz - Feel Good Inc.
Infected Mushroom - Song Pong
Attack Attack - Kissed A Girl
Doctor P - Bulletproof
Maximum The Hormone - Rock n Roll Chainsaw
Rob Zombie - Werewolf, Baby!
Escape The Fate - Gorgeous Nightmare
SOAD - Chop Suey
Ken Ashcorp - Absolute Territory
Machinae Supremacy - Need For Steve
Ozzy Osbourne - I Don't Wanna Stop
Crow'sclaw - Loudness War
Eminem - Rap God
Stromae - Humain À L'eau
Sonata Arctica - My Selene
Justin Timberlake - Sexy Back
Metallica - Fuel
Veil Of Maya - Unbreakable
Masa Works - Golden Japang
REOL - Luvoratorrrrry
Dope - Addiction
Korn - Word Up!
Papa Roach - ... To be Loved
Fever The Ghost - Source
Fall Out Boy - Immortals
Green Day - Know The Enemy
Mindless Self Indulgence - London Bridge
A static Lullaby - Toxic
Royal Republic - Addictive
Astronautalis - The River, The Woods
We Came As Romans - My Love
Skillet - What I Believe
Man With A Mission - Smells Like Teen Spirit
Yasuda Rei - Mirror
Mojo Juju - Must Be Desire
Falling Up - Falling In Love
Manafest - Retro Love
Rodrigo Y Grabriela - Paris
Zomboy - Lights Out
Muse - Resistance
T.A.T.U & Rammstein - Mosaku
Grey Daze - Anything, Anything
Katy Perry - Who Am I Living For
Maroon 5 - Lucky Strike
Machinae Supremacy - Killer Instinct
Pendulum - Propane Nightmares
Sirenia - Lithium And A Lover
Saving Abel - Addicted
Hollywood Undead - Levitate
The Offspring - Special Delivery
Escape The Fate - Smooth
Samsara Blues Experiment - One With The Universe
Dope - Rebel Yell
Crazy Town - Butterfly
Silverstein - My Heroine
Memphis May Fire - Not Over Yet

I hope my review is helpful to you!


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Reviewer at Headphonesty
Pros: Versatile, well-implemented sound signatures
- Flagship-tier sound quality
- Elite imaging and layering
- Very good accessory set, especially the ear tips
- Excellent fit and comfort
- Good isolation
- Reasonably priced
Cons: Generic design
- Heavy carry case
- Neutral tuning might be too sterile
- Treble is sometimes harsh
- Small soundstage
When you’re tired of the same old, same old; sometimes a switch is all you need. The Model X houses two changeable signatures so you’ll never be bored with the music.

Life is full of tough, petty, meandering choices, like chocolate/vanilla, money/fame, dieting/not dieting. Some you can go back and try the other, but others are substantial or large enough that you have to pick one and forever hold your peace, like a television, car or wife. At least until they give out lol.

In the IEM (in-ear monitor) world it’s just as tricky. You have a classic, followed by a variation of it, but with extra bass. History has given us VSonic GR07/Bass Edition, Hidition NT6/Pro, JH Audio 13/16, just to name a few. You tear your hair out poring through forums and reviews hoping to find a consensus (you won’t), since bass tastes, like fetishes, are extremely personal.

Like a little meme said, why not both? To have a regular signature, and also a bassier one when the mood (or curiosity) calls for it. Meaning you can have your cake and uh, have more cake. Lime Ears, a small company from distant Poland, practices this philosophy by incorporating a bass switch into some of their IEMs.

The switch was the main feature in their flagship, the Aether, and it has enjoyed great success because it’s basically buying two IEMs for the price of one. Today we look at Aether’s second-in-command, Model X. Mr. Spock to your Captain Kirk, if you will.


Black tie event, guys. Suit up everyone.

The Model X reviewed today is the universal version, housing 4 balanced armatures (BAs) in a 2 low, 1 mid and 1 high configuration. The X features Lime Ears’ in-house technologies:
  • PAR (Passive Acoustic Resonator)
  • VariBore
PAR is a sound bore tuned to even out the high frequencies; while VariBore uses sound tubes in optimized diameters for each frequency band.

And of course, the fabled switch. An easy flick up introduces an 8db boost to the lower-end frequencies from 800Hz down. Which means, for common folk like you and me, moar bass and a fuller, meatier sound. Hulk to your Bruce Banner. The Model X retails for €890.00 (~USD1000) and is available in universal or custom versions through their official website.

I’d like to thank Emil and Piotr from Lime Ears for their prompt communication and enthusiastic response in providing this loan unit. It’s been a pleasure talking to both of you.

This article was first published in Headphonesty.

Equipment Used


  • Sony NW-WM1A “K” Modded, FW 2.0
  • Lime Ears Model X
  • FiiO FA7
  • Jomo Audio Flamenco
Albums Listened
  • Bruno Mars – 24K Magic
  • Daft Punk – Random Access Memories
  • Ed Sheeran – Divide
  • Fleetwood Mac – Rumours
  • Jason Donovan – Greatest Hits
  • Macy Gray – Stripped
  • Prince – 1999
  • Taylor Swift – 1989
  • The Eagles – Hell Freezes Over

Packaging and Accessories

The Model X is packed with love. A prim, proper cardboard box greeted me, dressed in tuxedo black. The parcel felt unusually heavy, and now I know all the extra heft went to the aluminium case. You’ve heard of something built like a tank, well the case IS the tank. You can dent an actual tank with it, or knock a bird unconscious if you fling it in the air.

The case continues the tuxedo theme. Might be a coincidence that the Model X logo looks like a bow-tie when turned sideways, for unintentional class and charm! It’s roomy enough to hold the IEM, an extra cable, and all the ear tips for on-the-go. It’s heavy, but it will also outlive me.


The lunchbox of your dreams.

Completing the accessory set is the stock Plastics One cable, 9 pairs of ear tips, and a black cotton pouch. The branded ear tips are precisely what the world needs right now. A chocolate-box assortment of tips from Symbio (S, M, L), SpinFit (XS, S, M, L) and Comply (2 pairs M) mean the best in the market are provided, and you can definitely keep them for use with other IEMs.

I might have received special treatment because the cotton pouch is filled with traditional Polish cream fudge candy (krówki). You might or might not get them, but they’re sure delectable, and definitely contributed towards the final score of the review lol.

Design and Build Quality

The Model X marks the Lime Ears’ first foray into universal IEMs after making a career out of crafting only customs. It comes in an amorphous, take-it-or-leave-it shape bearing much resemblance to their custom brethren. A groove here, a bend there and a ridge in between, all in the name of comfort.

But in a stylistic statement of sorts, the X pairs dark smoke acrylic shells with black carbon fibre faceplates. The lime green logos break the monotony, imbuing a sense of playfulness, so things don’t get too formal or stiff upper-lippy. At the tip, sleek 2017A aluminium nozzles complete the look, with three bores of different diameters showcasing their VariBore technology.

There’s very little to fault with the design other than the overtly masculine appearance. I like to get in touch with my feminine side. As for build quality, they are as durable as your regular custom IEMs, meaning they’re plastic. Don’t step on ‘em, squish ‘em, or drop ‘em and you’ll be right as rain. Better yet put them in the aluminium case to survive World War III.


Extra marks for the delicious krówki, which translates to “little cows”.

Fit, Comfort and Isolation

When your bread and butter and bacon has been custom-fit IEMs, comfort and fit comes as second nature. I bet they could mold the Model X housing with their eyes closed. Sure enough, the X is a securely-fitting IEM, with comfort to spare for days and days. Have you ever looked everywhere for a sock only to realize you were wearing them all this time? Same feeling!

The amorphous shape might look like fascinating black jelly to you and me, but plays an integral part in the glove-like fit and supreme ease of wear. The switch, the only thing that doesn’t merge with the loving contours of the X, is located on the faceplate, and doesn’t touch any part of the ear anatomy.

Isolation is good, just about as good as a universal IEM allows. With SpinFit tips, I was able to keep the environment quiet enough for critical listening. In one instance, only after taking the Model X off did I realize there was construction work nearby. That’s commendable, unless the building is collapsing around you and you have no idea, then it’s bad.

Sound Quality

Think fast, what animal can change to adapt to new circumstances? If you answered chameleon you’d be correct, if you said “every living thing on earth” you’d also be correct. Not enough food? Eat less! Not enough sleep? Sleep more the next day! Too many children? Less sexy time!

While Model X hasn’t achieved “living thing” status yet, it comes with two sound signatures to adapt to listeners’ needs. The bass switch is there not just for the boom-boom. It can be activated to become more audible in low-volume listening, or turned on in a noisy environment for better immersion.

Overall Sound Signature

The Model X can be enjoyed two ways: dead neutral, or neutral-warm at the flick of a switch. The neutral sound is flat as an airport runway from bass to treble, but features incredible clarity and transparency like a dip in a chilly pool. It’s useful for studio monitoring, and some people do derive much enjoyment from a cold sound signature. Vengeful people maybe.

The other signature is friendlier to the ears and wickedly fun. With an elevated bass and lower mids region, instruments and male voices sound more full-bodied and correct in timbre. The mids and treble are unaffected from the base signature, so the note clarity and otherworldly detail are still mostly intact. It’s just a dip in a bubbly spa this time.

Listening Conditions

Critical listening was done after 50 hours of burn-in. BA-based IEMs normally don’t require burn-in, but I’m dense that way. A large chunk of the review was written while using Sony’s NW-WM1A Walkman modded by Project K, and the stock cable. The ear tips of choice were SpinFits, which convey the best seal, fit and comfort while not being detrimental to the sound.


Couldn’t find actual limes, so here’s something else that’s green.


Imagine yourself sliding into a skin-tight leather catsuit. Ok, you can’t, now imagine you’re Anne Hathaway. Easy does it. The leather adheres to the skin so securely nothing comes between them, like a vacuum. This is your Model X bass, skin-tight and airtight. The bass is as taut and disciplined as a supervillain or Batman’s on-again, off-again girlfriend.

The bass is, if you’ve been reading, lean and mean, with perhaps a too-quick decay. Extension is deep-reaching, but the sub-bass barely tickles your throat. You won’t feel the giddy heights of a pulsating sub-bass. The midbass conveys a tinge of warmth and body. Note hits are tidy, airy, and velvety-textured with great detail. In some passages, you wish there were more slam and impact though.

With the bass switch on, and it’s a brilliant change much closer to my preferences. Notes are made rounder, warmer and denser, sounding immediately more natural with a realistic timbre. However, there isn’t a satisfying, visceral sub-bass rumble, and the bass doesn’t move as much air as I like (my reference is a hair-dryer). Jokes aside, the switch is the game-changer for Model X and strews improvements across the signature.


Like traipsing in fields of daisies with no underwear on, the mids are airy, carefree and liberating. The attention-grabber of the outfit (or lack thereof), the mids are addictively crystal-clear and transparent. Notes possess just enough body to reflect a lifelike timbre, with a fun twist. Air follows each note like lovers’ gentle blows (don’t go there), lifting the signature skywards.

The layering is superb, perhaps elite-class. Even in busy tracks, you won’t lose track of what’s going on. You can pick out any instrument and just follow it like the stalker you are. Attack and decay are well-controlled as well. Notes flit in and out of the soundscape with speed and precision, aided by a bountifully black background.

The upper mids are acutely raised for all the airy, textury action to happen. So lady vocals and brass instruments are lively, articulate, and clear as a window, giving you an up-close, nothing-to-hide presentation that captures nuances like second nature.

The lower mids are flat and lackadaisical in neutral mode, but with the bass switch on, mamma mia! Male vocals, strings and guitars receive a welcome, robust boost of body, like a silicon injection in er, strategic spots, for rounder, firmer and dare I say more voluptuous notes. Seriously the bass switch is a godsend.


He hopes to land a role in a crime drama and finally be taken seriously.


Moving up from the clean and clear mids, the treble doesn’t deviate much from the baseline, if at all. Like a high heat sear, Model X’s treble aims for maximum impact in the shortest time possible, bringing the sizzle to an already vibrant signature.

Notes have a crispy edginess to them, especially at the lower treble region, veering towards brightness and stopping short of sibilance most times. Cymbals and hi-hats have a crunchy texture followed by a swift decay. Alas, sometimes the treble is overdone, leaving a burnt, charred aftertaste to an otherwise glorious meal. Too much bite and bark.

But 90% of the time, the treble is a people pleaser. The addictive skyward airiness, the lightning-fast transients, and the risk-taking, Evel Knievel extension that is brilliant yet dangerous, dares us to risk our ears and sanity to take in that massively detailed, ear-tickling treble that has as much sparkle as fireworks on the 4th of July.

Soundstage and Imaging

We like to trap stuff to admire in our own time. That’s why we put high-flying birds in cages, kidnap pandas so they’ll copulate to procreate, and uh, capture photos of food. The Model X’s light and airy presentation resemble a firefly that you’d like to hold in a glass jar so it only shines for you, you voyeuristic devil.

To keep the firefly happy, the glass jar is adequately spacious, but only just. The Model X has a tight, disciplined sound matched only by a tight, disciplined soundstage. It borders on the intimate, with equal height, depth, and width for an encompassing sound that never floats away, but serves the signature.

The imaging and separation though, is surely one of the best the market has to offer. With steely precision, layers are um, well-layered and intricate. Spatial cues are well-defined, you’ll have no trouble guessing what comes from where. This is all thanks to the brighter-edged, nimble notes working its mojo with plenty of black space to spare in the background. Ever wanted to dissect a song surgically? Now you can.


Dangle ‘em, tangle ‘em and mangle ‘em.


FiiO FA7

I didn’t mean to start this section with a pummelling, but unfortunately FiiO’s value-oriented FA7 is the only other 4BA IEM in my possession at this time. Again, at USD300 the FA7 isn’t exactly cheap, but when Model X is aiming for the heels of higher-priced flagships, you know FA7 has its work cut out to itty bitty pieces.

Let’s start with the positives. The FA7 showcases the continuing evolution of FiiO has a brand to be reckoned with, and is probably their most mature tuning to date. There’s plenty to like about the FA7, the robust build, head-turning faceplates, great fit and the accessible, warm sound signature.

It’s just that, when put against Lime Ears who’ve spent quite some time in the TOTL (top-of-the-line) arena, the differences are really telling. Model X obliterates FA7 in technical ability, boasting lengthier extension across both ends; cleaner, tighter notes with better definition and texture; a darker, airier background; and laser-guided imaging precision.


These blingy faceplates are built to hypnotise.

With that technical backing, Model X flexes its might in all departments. The bass hits deeper and more viscerally, and decays faster than FA7, sounding more engrossing and fun. Mids are more resolved and articulate, with crunchier texture and bite. The treble showcases much better micro-detail retrieval, and carries gobs of air wherever it goes.

FA7 is, by all means, a more forgiving, less fatiguing listen, and would be more of interest to those looking for a smooth, inoffensive sound. But overall, the Model X is a technical masterclass, with top marks in speed, precision, and fun. The FA7 is humbled, and made to sound blunt, slow and plodding while lacking air and crispness.

Jomo Audio Flamenco

Word association: when someone mentions “neutral monitor”, 9 times out of 10 I think of Jomo Audio’s Flamenco, their old flagship (not the Latin dance). It features 11 BAs with a killer neutral tuning, killer switches for bass and treble, and a murderous price (starts at a whopping SGD2999 or ~USD2200 depending on options).

While this might seem like a matchup between David and some giant, Model X and Flamenco are more spirit brothers, both carrying a neutral signature with switches to augment the sound. Flamenco has two fun buttons as opposed to Model X’s single switch, but for the sake of fairness, let’s just twiddle the bass switches.

Straight up, I was amazed at how remarkably similar they both sounded. They possess blazing-fast note speed, an eye for details, top tier transparency, a compact stage size and disciplined, razor-clean imaging. Like brothers from a different mother. The presentation too is similar, opting for precise, well-measured notes, immense air, and a bright tilt for excitement.

Before you can yell “doppelganger”, there are slight differences upon closer scrutiny. Flamenco sounds more organic, true-to-life, and effortless. There is an ease in which the notes flow into each other, and it scores massive points in musicality. This is achieved while not surrendering any of the resolution, speed and transparency that it is known for. It’s a proper top-tier monitor.

Model X however, sounds brighter, harsher and grainier than Flamenco. There is, unfortunately, a faint digital, metallic edginess to the notes, more noticeable in the treble. For mids, X leans towards articulation, while Flamenco has more accurate timbre. X’s bass is slightly boomier and more authoritative than Flamenco’s, lending a more V-shaped signature overall.

So Model X comes across as the excitable loose cannon, while Flamenco is more cultured, relaxed and provides minute refinement throughout. Next to the galvanic magnificence of Flamenco, Model X puts up more than a good fight. It’s flat-out amazing how well Model X keeps up despite the price difference. Baby Flamenco? Why yes!


If only it was a working timepiece.

Final Words

We like to look for the one IEM that can do it all. But no matter what we choose, concessions are made. Too much clarity sacrifices naturalness, too much note body foregoes airiness and congests the stage, too much smoothness puts you to sleep, too large a soundstage diffuses the sound and lacks engagement, et cetera et cetera.

Finding the perfect IEM is more of keeping what you want while accepting as little shortcomings as possible. It’s a balancing act, like walking a tightrope to profound madness. Lime Ears doesn’t have the solution, or “the one”, but proposes a workaround that allows you to have the best of two worlds, a reference and a fun signature, covering a great many genres in one swoop.

As some might say, X marks the spot. Or is it X barks the lot. Or maybe X sparks the thought. Enough. Model X is quite possibly the most versatile and accomplished IEM I know of in its price range, and provides much ammunition for the “you don’t need many drivers for great sound” argument. What’s more, Model X dares to dream, with technical abilities that rock the boat of pricier flagships.

History remembers the best duos in memory, like Lennon/McCartney, John/Taupin, Milli/Vanilli, bacon/eggs… anything but those Wham! guys. In the same rich vein, Model X’s dual signatures are different and dazzling enough to stand on their own, a dastardly duo that does it all to discerning and distinguished devotees. It’s an absolute joy to listen to.


100+ Head-Fier
Pros: Fabulous SQ
2 fab sound settings
Comfortable (for me)
Holographic sound stage
Oodles of Details
Sublime imaging and separation
Cons: May be too big for smaller ears
Crappy cable
Slightly rough finish around switch
Quick Read Conclusion

I joined the review trail for the Lime Ears Model X (universal) (“Model X”) reasonably excited about the proposition of switchable tuning. I have seen a number of IEMs including this sort of functionality over the last few years, and the Model X was the first I got my hands on. The Model X is a remarkable bit of kit – two IEMs in one really; at first, you have a very neutrally tuned detail master, then flick the switch and the corresponding lift to bass and lower mid frequencies gives a much more relaxing and (to my ear) enjoyable experience. Rounded off with (other than the cable) a solid set of accessories and the Model X offers a convincing proposition for relieving yourself of €890.

Introductions and General Bumf

This review follows a familiar format, but I have spent a little more time deliberating on the comparisons between the two switch settings of the Model X – as it is clearly a key feature, I thought worth some focus.

For the avoidance of doubt, I am in no way affiliated with Lime Ears and have received no inducement from them to write this review (apart from a bit of fudge they included with the review sample, but as it was Lent and I had given up sweets etc, my wife ate it. Apparently lovely!).

Test Kit: I have tested the Model Xs with a Samsung Note 8 and Galaxy S8 (using both UAPP and Tidal), an 11" Macbook Air (2012 vintage, running Tidal), an Astell and Kern AK70 mk 1 (both balanced and unbalanced), an iFi iDSD Nano Black Label, RHA DacAmp L1 and also a Schiit Modi 2 Uber into a Vali 2 ("Schiit Stack").

Preparation: I received the Model Xs as review samples and gave them both about 50 hours of burn in before any analytical listening.

Me as a listener: I am not a pro by any stretch of the imagination. I have always enjoyed my music, and my tastes are pretty broad. I go to live music ranging from rock and pop concerts to orchestra and opera. I would not describe myself as having a trained ear, but I am attentive and my ears are in pretty good nick for a 35 year old.

My tastes: neutral to warm, but I do like good punchy bass and I love to hear decent instrument separation.

Test tracks: Test tracks noted in the review below were the TIDAL 16/44.1 available through their Hi-Fi subscription.

So, on to the main event. [/General Bumf]

Tech Specs

Now this is an interesting one. I struggled to find detail of the normal specs (impedance, sensitivity, THD etc) I would expect to publish as part of a review on the Lime Ears website, so I dropped the (ever helpful) Peter a line and the response was “… we kinda don't believe in these. That’s funny considering we are a pro-audio rather than audiophile company… [and published stats] are often bogus”.

I’m a little conflicted by this response. I have always been clear in my reviews that I am an amateur reviewer, and focus on trying to describe what I hear when listening to the equipment. From this perspective I get Peter’s point. However, I think that stats and frequency response curves can be extremely helpful in helping make sense of what I’m hearing – recognising impedance mismatch as a source of distortion for example, or identifying a frequency response spike as a perceived focus on a particular part of the sound spectrum. Peter did share some internal measurements Lime Ears had, but asked me to keep them to myself. I have respected this, but I would say that:

1) they were excellent and I don’t think he should have any problems sharing them in this community; and

2) they correlated with my subject perceptions… helped to make sense of what I thought that I was hearing.

So what can I say unequivocally? The Model X contains 4 balanced armatures and utilises Lime Ears’ Passive Acoustic Resonator and Varibore technologies (more detail at, but basically physically adapting the sound bores in the IEM nozzle with the intention of producing a better sound). In my experience, including plugging the Model X into my Vali 2, I didn't encounter any impedance distortion.


Lime Ears are another IEM manufacturer which have nailed quality, premium packaging perfectly. When I received it, I was really surprised by the weight of the box – the heaviest IEMs I have ever been shipped. On opening the box, it was clear why… the Model X come with their own solid metal tin. Nice touch and no question this will protect the IEMs adequately.

In the box then, that tin containing the Model X IEMs, and their 3.5mm unbalanced cable (more on that below), and a bunch of tips, all inside a thick card box with a magnetic flap and ubiquitous Lime Ears branding. And the obligatory warranty card etc.

UB1.jpg UB2.jpg UB3.jpg Metal Case 1.jpg Metal Case 2.jpg



Lime Ears obviously have the same cable supplier as fellow Polish IEM manufacturer Customart… and they should both sack them off. An average, inflexible cable with poor (i.e. too much) microphonics (especially due to rub against glasses) and an overall cheap feel. I abandoned it immediately and used my Effect Audio Origin cable, including for all testing below. In my opinion, at €890, Lime Ears should be including a superior cable – the EA Origin is only US$60 but immeasurably superior to the included cable.


Conversely, Lime Ears included a fulsome set of tips including (my personal fave and the tip I settled on for testing) Comply foam tips, a number of silicon spinfit style (not sure if they are actually SpinFit), and a really interesting silicon outer, foam inner tip which I loved the idea of but found a little uncomfortable.

Practicalities, Build, Fit and Tips

You can tell the Model X is built by a custom IEM manufacturer – they are big, and consistent with a lot of the premium custom manufacturers’ universal offerings (with the possible exception of 64 audio), chunky. The nozzles are also pretty long and wide, so they go deep into your ear canal. This meant that I actually couldn't use the usual Comply tips I like to use (the ball shaped ones) as I couldn't get the Model X deep enough inside my ear canal. I also let my wife (who has small ear canals) have a listen, and even with the smallest comply tips, she was struggling to get them into her ears. Once you get the right tips though, fit, seal and isolation are all good. My recommendation on fit then – try them first if you can! You’ll see from the pictures below though, that once properly inserted they are pretty neat and snug.

Nozzle.jpg Nozzle View 2.jpg Nozzle View 3.jpg In ear1.jpg In Ear 2.jpg

Build quality is (with one small exception) great. Seamless faceplate attachment onto a comfortable acrylic body – the carbon fibre finish of the faceplate set off against the (lime!) green motifs is deeply aesthetically pleasing to my eye, and the Model Xs are a joy to hold with a sensible weight to them. My one tiny niggle (which I feel justified at this price point) is that, around the switch, the finish is a tiny bit rough. No suggestion anything will break/fall out, just that the slightly unfinished feel around the switches is noticeable on an otherwise beautifully fabricated IEM.

Back show rough.jpg

The Sound

The Switch

The main event here is the switchable tuning. In the switch down (reference) setting, the tuning is very neutral and (to my ear which prefers a little more warmth and bass) a little thin sounding. Unquestionably treble forward and (after a while) a little fatiguing. Flick that switch to the up (warm) setting though, and you are hearing a different IEM – the lift in the bass and lower mid provided by changing the tuning taking off some of the sharper edges and creating a much more relaxed sound, possibly at the expense of a little detail.

I had a good few weeks with the Model X (for which I thank Lime Ears), including taking them on holiday with me. Initially I only listed to them on the switch up (warm) setting, finding the switch down (reference) tuning thin, dry and a bit fatiguing. One evening however (after the best part of a bottle of a very good South African pinot noir) I decided to listen to some live guitar focused music (Barenaked Ladies live album on Tidal) and was blown away by the soundstage and detail I was hearing in the recording, really experiencing “holographic” sound stage. I then became much more experimental with the tuning switch, finding that different tracks were better suited to different tunings – the positive and negative traits of each tuning being:

Switch down (reference) – sparkly treble, massive soundstage and enhanced detail but I found I needed to listen to the Model Xs louder on this setting, and this made them a little more fatiguing. On certain tracks this setting can also sound a bit thin/lifeless.

Switch up (warm) – much more laid back, relaxed and fuller sound, but can introduce a little mud/veil to the track.

Highs, Mids and Lows

Switch down (reference)

Best suited to guitar (especially steel strung), live and orchestral pieces, the Model Xs in this setting really focus on that upper range, sparkling in “metallic” frequencies – cymbals, triangles etc but lacking a little for any sort of music which has a requirement for impactful bass (think most pop, EDM, rap etc). One of my favourite tracks for testing bass – Wiz Khalifa’s On My Level, is a very different proposition switch up. You can hear the bassline but there is no impact, and the treble snare is far more forward. Vocals, especially male vocals, can also sound a little lifeless in this setting to my ear. Pearl Jam’s Yellow Ledbetter for example losing some emotion as the vocals have less impact and power than Eddie Vedder deserves!

Switch up (warm)

For me, my default setting with the Model X, the bass enhancement creates a non-fatiguing, more impactful sound. This is still balanced armature bass, you are not being blown out of your seat, but the difference is clear. Switch to something like Fouki’s Je Positif, and there is depth and focus in (male rap) vocals with the (low mid) trombone fully occupying centre stage, not demoted below the consonant of the vocals.

Both1.jpg Both 2.jpg

Soundstage, Separation and Detail Retrieval

Switch down (reference)

The level of detail retrieval and the soundstage created by the Model X is a real strength of this IEM. The soundstage is broad with clear instrument placement, but on the right track (almost any live recording) there is a spectacular holographic soundstage, creating not just width and depth but an intriguing sense of height. These Model Xs create a truly capacious overall stage (particularly for an IEM) but manage to place instruments well on it. For example, the Santana/Rob Thomas classic Smooth sees an obvious placement of bongos left and high, Rob’s vocals up front and the washboard over right and high, with the brass section front and centre but low. This placement is palpable, almost causing you to cock your head to hear a specific direction a little better.

Switch up (warm)

The same as above, but with a little detail, space and holography missing. The cost of relaxing warmth, a little less detail, a shrunken soundstage and a less discernible physical placement with a shrunken soundstage.

Gear Matching

I found the Model X to scale beautifully with any kit I threw at them. My mixture of dacs and amps noted above all scaled will, with the Model X's able to extract the finest detail. Where they surprised me was plugged into my Schiit Stach (Modi 2 Uber into Vali 2). Given the tube this is normally noisy with IEMs, and SQ suffers. Not so with the Model X - there was the ever-present tube buzz but they maintained their signature soundstage and detail retrieval where other IEMs often fail. Usable in a desktop environment then.


v. Customart FIBAE Massdrop Edition (custom)

Nothing like the bass impact that the FIBAEs can deliver, but superior detail (even on switch up – warm). Far more subtle, leaving the FIBAE ME’s sounding a little veiled in comparison.

v. Campfire Audio Polaris

With switch up, some similarities to the very V shaped tuning of the Polaris. Bags more detail, quicker decay and more overall coherence creating a more physically accurate sound. Hard to describe, but (for example) an oboe sounds much more like a real life oboe as opposed to an approximation of one. More… lifelike.

With RHA DacAmp L1.jpg


Cable is poor as noted above. Easy fix Lime Ears.

Switch bore could be a little smoother/better finished. Maybe a gromit?


Our friends at Lime Ears have done something a bit special here. Two premium IEMs here in one pleasing package: a reference tuned detail monster with a soundstage to die for; neatly transitioning to a warm, enjoyable leisure listener. As I sit, on the train home, flicking between switch settings to suit the tracks I am listening to, I struggle to think of a more satisfying (or greater value) method of relieving myself of (a bit less than) a thousand euros.


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Reviewer at The Headphone List
Pros: Outstanding versatility
- Exquisite balance of smoothness and clarity
- A realistically-structured midrange
- Beautifully-refined treble
- Switchable bass response
- Great build quality
- High value-for-money
Cons: Not the last word in resolution and transparency
- Imaging precision isn't its strongest suit
- Okay bass extension, texture and physicality
- Average packaging and accessories (for now)
DISCLAIMER: Lime Ears provided me with a discounted price on the Model X in return for my honest opinion. I am not personally affiliated with the company in any way, nor do I receive any monetary rewards for a positive evaluation. I’d like to thank Lime Ears for their kindness and support. The review is as follows.

Lime Ears is a Polish in-ear manufacturer whom – I think – is one of the most underrated in the world today. Three years after the release of their highly-acclaimed flagship Aether, the company have set their sights on dominating the mid-tier market with the all-new Model X. However, despite its positioning as second-fiddle to the Aether (in driver-count andprice), company founder Emil Stolecki has equipped the Model X with both old and new innovations inside. The bass switch and VariBore make welcome returns, while PAR (or Passive Acoustic Resonator) technology makes its debut – resulting in a vibrant monitor with smoothness, air and headroom to spare; one of the most versatile 2018 has to offer.

ModelX-5 (2).jpg

Lime Ears Model X
  • Driver count: Four balanced-armature drivers
  • Impedance: N/A
  • Sensitivity: N/A
  • Key feature(s) (if any): PAR (Passive Acoustic Resonator) technology, VariBore, switchable bass response
  • Available form factor(s): Universal and custom acrylic IEM
  • Price: €890
  • Website:
Build and Accessories

The Model X arrives in a black Pelican-esque monitor vault with the logo, owner’s name and serial number printed on top. The in-ears themselves are nestled safely inside, along with a cleaning tool, desiccant and a name card with Lime Ears’ contact information. Like I was with the Aether, I’m a tad let down by the minimality of the package. I expect more in 2018, especially considering my experiences with Avara Custom, Empire Ears and AAW. But if what I saw at CanJam Singapore 2018 is to be believed, Lime Ears should soon revamp their packaging to adopt a more luxurious aesthetic – complete with a sizeable box, a metal case, and ample accessories. Unfortunately, I can’t review what I do not have.

ModelX-15 (1).jpg

Despite the modest packaging though, the monitors themselves are gorgeously built. Emil and I decided to experiment on a brand new design option for the Model X, and the result is a beautiful marble-like motif. Completing the scheme are a pair of engraved logos and a coat of lacquer. The shells are a tad light, but they’ve survived tons of gigs in my fully-stocked backpack, so this shouldn’t be of much concern. Ergonomically, the Model X is one of my looser-fitting monitors – ironic considering the Aether is one of my tightest. However, this is no real detriment to comfort or isolation at all. The Aether’s do cancel out a touch more noise, but I’d rather take the Model X’s vanishing comfort any day. So all in all, I think Lime Ears is an underrated force in cosmetic design and build. All they need now is a premium package to match.

VariBore and PAR Technology

Drawing from Emil’s past experience as an acoustics engineer, VariBore and PAR technology are both acoustical mods. VariBore implements varied sound bore diameters for the low, mid and high frequencies. The dual bass drivers fire through a tighter 1mm bore for optimal low-end delivery, while the tweeter outputs through a 2mm bore for superior extension and minimal resonance. When paired with further damping, the driver delivers a silky smooth top-end that doesn’t skimp on energy, vibrancy or air; one of my favourite elements of the Aether that makes a return in the Model X.

ModelX-3 (1).jpg

On the other hand, PAR manifests itself as an additional bore bred purely for resonance control. It’s an empty cavity that acts as a resonator, further smoothening the Model X’s frequency and impulse responses. By treating the ear canal as an acoustics engineer would a room, Emil has given the Model X an advantage over the Aether in transient speed (and decay), overall authority and resolution despite the latter’s higher driver count. These improvements in focus and finesse address the Aether’s most common criticisms – especially in the midrange – and allow the Model X to maintain its dynamic, musical and fun signature with very little compromise in cleanliness and transparency along the way.

The Switch

Lime Ears’ bass switch is another recurring feature present in the Model X. It boosts frequencies below 800Hz by approx. 6dB. It’s an especially useful feature when listening to playlists with varied genres, but it’s also compliant to the Fletcher-Munson curve. Basically, the curve states that at lower volumes, the human ear will perceive less bass relative to the mids and highs. So, this bass boost compensates for that in scenarios where quieter listening is ideal or required.

The Model X leans toward neutral with the switch down. This is unlike the Aether, where its bass remained musical in the same position. With the switch up, the low-end gains dynamism, impact and body with little alterations (if any) to tone, as well as minimal compromise in imaging. The technology may be more widespread nowadays, but Lime Ears’ implementation remains one of the best – adding energy when the mood strikes with little cost to balance or finesse.


The Model X boasts a fun, musical and well-balanced sonic image. Like the Aether, it draws from massive headroom to create an open, airy and especially smooth presentation. But, one shouldn’t mistake this effortlessness for a warm, laid-back signature. Conversely, the Model X’s generous presence across the upper-mids and treble create an exciting ambience. Instruments are vibrant, clear and well-resolved – painted against a decently black background. Its stage may not be the largest of its competition, but this benefits its engagement. There’s sufficient space for full stereo coverage across the head, but enough intimacy is also maintained so the presentation never feels dull or nonchalant.

ModelX-2 (2).jpg

A key element in the Model X’s tonal balance is its lower-midrange. Standard practice dictates a dip in this area for max definition, but Emil cleverly bypasses this for greater linearity and superior vocal structure. Notes are sufficiently wet, rich and full-bodied, yet never muddy, bloated or congested. Clarity is then drawn from quick decay and decent treble extension. The stage does retain traces of harmonic haze – so to speak – but the Model X nonetheless maintains some of the best balance between richness and resolution in the sub-$2000 market. Its tone adopts a light shade of warm; leaning closer towards neutral than natural. But, the Model X bolsters more vibrant and melodious instruments than the flagship Aether, because of a more controlled mid-bass, a more resonant midrange and a more articulate upper-treble.


The Model X’s low-end is emphasised towards the mid-bass – consistently producing punchy, fast and musical throbs. Extension only experiences a marginal improvement over the Aether, so it’s still not the most well-defined or textured bass in the world. But conversely, superior treble extension endows greater control over mid-bass bloom. This results in less bleed towards the midrange and higher resolution down low. Nevertheless, the bass’s very light warmth imparts body to vocals and instruments alike, and linearly connects it to the lower-midrange. This is further escalated when the bass boost is active, while the low-end is more tightly reserved – and the stage becomes cleaner – with the switch down.

In both settings, the Model X maintains a warmish-neutral bass tone; only becoming a touch warmer with the switch toggled up. This aids layering and transparency. But on the other hand, the Model X’s bass can never be as gutsy and dominant as the Aether’s can. This is a low-end tuned with a decisive aim towards balance and midrange transparency, so listeners who found the Aether’s bass barely sufficient may not prefer the Model X’s lighter delivery. Speaking of balance, in switch down mode, the bass sits linearly with the midrange; just behind the upper-mids. With bass boost activated, the low-end moves just past the upper-mids for a fuller response. Here, you’ll get a busier stage with a touch less finesse, but both settings will appease a wide variety of listeners and genres – so long as they aren’t bassheads.


The midrange is where the Model X truly surpasses its bigger brother – superior in structure, focus and transparency by admirable margins. A laid-back lower-midrange fuels definition and contrast, but – again – enough content is present for impressive vocal integrity. A rise escalating throughout 1-3kHz give instruments palpable presence, finished with a 5kHz peak for articulation. Most impressive, however, is the linearity with which the rise occurs. The Model X constructs an impressively coherent midrange with zero noticeable aberrations until its lower-treble. This results in a stable, cohesive image, and marvellous headroom – which, in turn, bolsters realism despite the relaxed lower-midrange. Lime Ears have absolutely nailed smooth transparency down to a science, and nowhere is this clearer – literally – than on the Model X.

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In tone, the Model X maintains a gorgeously smooth, lightly warm timbre – neutral-leaning with the bass switch down. But, the midrange’s MVP is certainly its clarity. The Model X carries gobs of headroom and air; as if the vocalist were belting within an open, endless space. There’s a powerful, resonant quality to instruments too, which I attribute to the passive resonator. This compensates for utmost resolution, which is very lightly smudged by the Model X’s treble extension. Nevertheless, when price is taken into consideration, there’s more than enough air to bask in and imaging precision remains decent – if not pin-point. An upper-mid bias is present, so instruments are more melodious than they are weighty. But, once again, excellent coherence preserves realism; sufficiently life-like with every track thrown its way. Truly, this is where the Model X’s most impresses; a midrange as unwaveringly smooth as it is stunningly clear.


The Model X’s midrange may be its most improved component, but the treble – as with the Aether – remains its best. Subtle peaks are present along 5, 7 and 12kHz, but Emil has taken the extra mile to ensure seamless integration for all three. Needless to say, he has wildly succeeded. The Model X’s top-end is crystal clear in tone – and outstandingly airy as well – but at the same time, it is uncannily smooth. It’s an almost paradoxical treble that I’ve yet to hear in any other IEM (besides probably the Vision Ears VE8). The region as a whole is outstandingly linear and coherent, while the subtle peaks add elements of attack, crispness and energy where necessary. If treble were decided by timbre and cohesiveness alone, Lime Ears would have a clear winning formula on their hands – smooth, airy, refined and satisfying at all times.

But alas, additional aspects must be considered too when evaluating treble. One is extension. Relative to the Aether, the Model X extends a touch further; displaying a cleaner stage and greater low-end control. But, it still lacks that last bit of reach for utmost transparency. As mentioned previously, the Model X carries a touch of harmonic haze. Although this aids musicality and cohesiveness, it’s to the detriment of imaging. Instruments are large, vibrant and engaging, but there’s some overlap as to where they are on the stage. In its price rage, it faces stiff competition from the Custom Art FIBAE 3, the 64Audio A6t and – especially – the Kumitate Labs Meteo, so great performance here is crucial. Nevertheless, it just trumps all three in placement, linearity and coherence. A silky quality within the Model X’s top-end integrates it soseamlessly into the bigger picture, that it exists both as a team player and as the monitor’s undoubted star performer.

General Recommendations

The Model X has a clear, well-balanced and forgiving signature that makes it suitable for a massive variety of genres. It does come with a couple compromises to achieve this; settling for a jack-of-all-trades approach rather than satisfying any niches. But nevertheless, these are groups who’d benefit most from its smooth, clean and energetic presentation:

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A musical, clear and full-bodied all-rounder: As I’ve made crystal clear throughout this review, the Model X is a do-all IEM. It boasts bounds of openness, clarity and air to satisfy the busiest of genres and its midrange carries enough density for slower, more emotional ones as well. Rock and electronic music will benefit from its tolerance for harsher recordings, as well as its penchant for dynamic energy. On the other hand, jazz and classical aficionados may find a need for tonal warmth, but the in-ear’s excellently executed 1-3kHz rise ensures palpable physicality for vocals and instruments alike.

Clarity and vibrancy without sibilance: Smooth transparency is one of the Model X’s prime strengths. The musicality of the upper-mids – as well as its linearity along the treble – gives the in-ear a breezy, air and pleasingly clear tone. But, the balance it maintains with regards to the mid-bass and lower-midrange is crucial. As a result, its clarity is constantly buoyed by a sense of body and integrity; not the false, grating clarity that’s been infecting the market as of late.

A variable bass response for different moods, genres or playlists: The Model X’s bass switch makes it wonderfully versatile for a variety of listening scenarios. Additionally, it’s implemented in such a way that it adds weight without altering much of the in-ear’s inherent tone. Of course, whether or not that’s a pro depends on whether or not you enjoy the Model X’s house sound. But nevertheless, it’s a dandy feature with excellent practicality, ease of use and minimal compromise.

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However, despite the Model X’s agnosticism towards production quality and genre, it does have a specific colouration and bias that people may or may not enjoy. It leans closer towards fun, breezy musicality, rather than cold analysis orlush, euphonic warmth. So, the Model X may not be for you if your preferences lie within the following categories:

Utmost precision in imaging and stage expansion: Although the Model X is wonderfully clear in tone, it isn’t as transparent as far as space is concerned. One of the sacrifices it makes in achieving cohesive musicality is pin-point imaging. Additionally, as treble extension begins to waver, its stage isn’t the most clinically defined either. So, if you’re an opera nut with an affinity for theatre halls or two-storey-high church auditoriums, the Model X might not be your cup of tea.

A guttural low-end or a wholly-developed midrange: The Model X is a jack of all trades, but that also makes it a master of none – apart from being variative, ironically. So, it doesn’t necessarily lean in to any cliques, which limits its appeal to niche crowds. Bassheads won’t appreciate the Model X’s leaner low-end and its midrange – while clear – lacks the necessary texture and tonal finesse to truly appease vocal aficionados. It works well enough with genres like classical and jazz (as mentioned), but won’t be the be-all-end-all for those genres – or any genre for that matter- either.

Rich, buttery tonal warmth: The Model X is a well-balanced IEM with enough density and fibre to support its presentation without fatigue. But, there’s a noticeable lack of warmth – particularly in the bass. The Model X is a reasonably neutral IEM, and some might not enjoy its lack of euphony. Granted, to make room for that richness, the Model X would need even more headroom and stability than it has now. So if anything, this is something Emil can strive for in the future.

Select Comparisons

Lime Ears Aether (€1150)

The Model X and its bigger brother share many similarities. They’re both smooth, musical and airy IEMs hallmarked by an open treble response and outstanding headroom. However, they do differ in presentation and balance. The Aether is decidedly richer and heftier because of its fuller mid-bass and more withdrawn upper-treble. The Model X has a flatter, tighter low-end along with a crisper upper-treble, resulting in a more neutral tone and cleaner delivery. This also gives the Model X a blacker background and cleaner separation, even though stage expansion and imaging are similar.

The bass is probably where the Model X and the Aether are least alike. The latter has a significantly warmer, richer and bloomy-er mid-bass, while the former’s is tight and controlled. The Model X’s low-end is cleaner, brighter and better-layered by a significant margin. Paired with its energetic upper-treble, it feeds far less bleed into the midrange. But as a result, its bass is a lot less lush, melodic and musical relative to the Aether. Some may prefer the clearer, more compact approach, while others will find more value in the Aether’s fun, energetic delivery (despite its technical shortcomings).

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The midrange is where the Model X has most improved from its bigger brother. A tighter mid-bass provides a cleaner, blacker background, while a brighter upper-treble boosts clarity and contrast. But, where the Model X truly pushes forward is speed and resolution. The Aether has drawn criticism for its almost unfocused midrange; slightly withdrawn and diffuse, despite its tonal charm. Fortunately, the Model X offers a more complete and fleshed-out presentation with greater holography, solidity and depth. Instruments are snappier and denser, while the Aether remains calm and laid-back. The Model X may sound a touch brighter and lighter, but in terms of technical performance, it takes the cake.

The two Lime Ears monitors share fairly similar treble responses – airy, fast, open and yet smooth. This is especially true of the lower-treble. Both peak around 5kHz with a similar amount of energy relative to the midrange. However, the Model X is more energetic in the upper-treble; around 10-12kHz. As mentioned earlier, this is what gives the Model X its superior sense of cleanliness and clarity, as well as its relative neutrality. So, the Aether is probably more linear up top, but the Model X’s technical benefits can’t be ignored. Extension goes to the Model X as well, resulting in its blacker background, more stable stage and increased headroom. Imaging may be on par, but it’s delivered more effortlessly.

64Audio A6t (w/ M15 module) ($1299)

The A6t and the Model X sound like they were raised in similar households. Both are neutral-natural – with a tendency to lean towards the former – with an emphasis on midrange solidity and treble performance. However, in their respective quests to achieve that goal, they differ in approach. The Model X is more involving, intimate and musical – engaging with forwardness, vibrancy and air. Conversely, the A6t is more laid-back – choosing to envelop the listener with an emphasis on stage stability and background blackness, while the solidity with which instruments are presented lulls the listener in.

Unlike the Model X’s mid-bass emphasis, the A6t has its bump somewhere between the sub- and mid-bass. This is a presentation that invites more texture; visceral and guttural in its delivery, aided by decent extension. Comparatively, the Model X’s low-end is cloudier with a softer, silkier sense of impact; the A6t being the more physical and solid of the two. The A6t is darker down-low, but possesses great layering and clarity. The Model X loses out in this regard, opting to fill the stage with detail coming from the midrange and treble, rather than the low-end. In balance, the A6t is more akin to the Model X with the switch up, but its pitch-black background gives it the headroom to do so with relative ease.

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In the midrange, both IEMs possess a 1-3kHz rise for excellent body and density. However, the Model X displays more energy in both the lower- and upper-mids. As a result, instruments sound more vibrant, forwardly-placed and resonant. The resulting images are rather loose and radiant, resulting in the harmonic haze described earlier. Conversely, the A6t is more even-handed and nonchalant here. Instruments and vocals are more compactly-sized and dense, which aids its imaging and resolution. But in the long term, some may find the Model X’s more musical presentation more enjoyable. In tone, they both err towards neutral due to their upper-trebles, but realism is maintained in structure and delivery.

The Model X has a smoother, silkier treble response compared to the A6t. The former peaks at 5kHz, while the latter rises closer to 7kHz. The A6t will display more solidity, definition and realism as a result – particularly with instruments like hi-hats and cymbals. But, poorly-produced tracks may end up sounding brittle as well. Because of its vibrant upper-mids, the Model X displays better integration of the treble into its overall soundscape. On the other hand, the A6t – depending on the pairing – may have its top-end a touch more forwardly-placed than its upper-mids. It’s a matter of preference whether you enjoy the Model X’s clearer tone or the A6t’s more defined, compact presentation. Regardless, the A6t is the clear winner in extension, decided by its superior precision, transparency and background blackness.


The Lime Ears Model X makes yet another compelling entry in the mid-tier market and displays remarkable maturity in the company’s house sound. Filled with much of the flagship Aether’s DNA, the Model X takes advantage of old and new technologies for further gains in resolution, speed and finesse. The result is a vibrant, clear and seductively smooth monitor fit for any genre thrown its way. Although by no means the most technically-acrobatic of its ilk, only few can contest the sheer enjoyment bleeding through its airy, open soundscape. The Model X is Emil Stolecki flexing his acoustical muscles to make one of the most charming and easily-enjoyable, all-round IEMs I’ve heard yet. Proceed on this path with a focus toward technical performance, and Lime Ears will be an absolute one-to-watch for years to come.

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