Review: Lime Ears Model X – The Gift of Duality

Black tie event, guys. Suit up everyone.

We independently review all our recommendations. Purchases made via our links may earn us a commission. Learn more ❯

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.

Black tie event, guys. Suit up everyone.

Lime Ears Model X

“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.”

What We Like 😍
  • 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
What We Don't Like 🤢
  • Generic design
  • Heavy carry case
  • Neutral tuning might be too sterile
  • Treble is sometimes harsh
  • Small soundstage


via Gfycat

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

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.

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 aluminum 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.

Hot Tips

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.

Editor’s note: Lau is joking about the contribution of the sweet to its review. Please do not send us any complain letters. Peace out~

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 fiber 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 aluminum nozzles complete the look, with three bores of different diameters showcasing their VariBore technology.

For Manly Men

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 aluminum 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.

World of Silence

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.

Flame on!

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.

A Little Dangerous

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.

Like Onions

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.

It’s Not All Bad

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.

Ivy League Muscles

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.

Dust Brothers

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.

Devil in the Deets

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.

Aiming High

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.

Leave a Reply