Earsonics Onyx Review

Earsonics Onyx Review

8 April 2022 0 By Petros Laskis

Black Magic

Pros: + Balanced and musical tuning
+ Great bass extension with good technicalities
+ Lush mids and fatigue free treble
+ Crystal clear and resolving
+ Expanded soundstage with accurate imaging
+ Coherent timbre
+ Great looks and mostly comfortable fit
+ Excellent build quality
+ Cable of good quality
+ Handcrafted in France

Cons: – Bass can sound hollow
– Could do with greater dynamic impact
– Upper – mids emphasis
– Some issues with treble timbre
– Bulkier and heavier than the competition
– Poor accessories pack
– At this price point a modular cable should have been included

The Onyx was provided free of charge in exchange for my honest and subjective evaluation.
The selling price is €491.67 and it is exclusively available from Earsonics.

About Earsonics

Earsonics was founded in 2005 by Franck Lopez, a musician and sound engineer, who, unhappy with the quality of in-ear monitors available at the time, decided to create his own.
In 2006, he began to offer his creation for sale and enjoyed immediate success, even equipping the biggest French music tour at the time. Earsonics was born !
Franck then decided to release a mainstream model which would appeal to markets outside of France…the SM3. The resulting product reviews expanded product awareness into the Asian and North American markets, with the SM3 considered the finest earphone ever tested.
In 2012, Earsonics launched the first universal 6 driver earphone in the world, the S-EM6. Entirely made by hand, its musical qualities garner universal praise in numerous tests.
In 2016, Franck decided to create the best universal earphone in the world, using the many advances and technologies developed up to that point – the S-EM9. With nine drivers and three exit ports per side, the aim was to be able to listen to music exactly as it had been recorded.
From its very beginning, Earsonics has always been associated with professional musicians, and it is by developing products for this industry that it has been able to offer earphones of exceptional quality to the discerning public.
More information about Earsonics and their full catalogue can be found here.

The Onyx is not my first encounter with Earsonics as I have previously reviewed the Corsa.


The Onyx project

The Onyx concept was born in a confinement context.
The team of enthusiasts engineers in charge of its development wondered what could be the best earphone that would meet the current requirement of the audiophile public.
What started out as a concept turned into a real project.
The ONYX was born.
This team of passionate people, the heart of the ONYX project, designed it based on the knowledge and know-how used in the Earsonics laboratories.
After several months of work, the first plans for the ONYX were alive and with them the beginnings of an exceptional earphone.
To develop the ONYX, using the best materials was the leitmotif of the team.
When developing it, the engineering team used the best.
Thus, the ONYX is based, among other things, on the latest generation of 3D acrylic core used for the Grace Platinum, Earsonics flagship.
The specific inclination of the ONYX body and cannula is the result of many years of research guaranteeing a comfortable fit and better insulation.


Direct sales

The project goal is to offer a very high-end universal in-ear at a price never seen before.
It was therefore necessary to reduce distribution and processing costs as much as possible.
In order to achieve this, Earsonics decided to set up a direct sales website for ONYX without any intermediaries.
The ONYX is exclusively available to order on its dedicated page.

Handcrafted in France

Entirely handcrafted in France, the ONYX is designed to offer the highest level of quality at an unbeatable price in its range of high fidelity headphones.
This result underlines the commitment of the engineers on this project to satisfy the most demanding audiophiles.


The internal structure is made of acrylic and it is supported by a skeleton of the same material allowing it to beat at full speed while avoiding the problems associated with sound reverberation.
The ONYX can be matched with all electronic systems and its unique TrueWave technology guarantees a pleasant sound reproduction, without major imperfections.
The TrueWave system is a “3” asymmetrical output cannula topped by a mono–brass bell.
All of that leads to an optimal phase control and a prime magnitude coherence curve.
The Onyx is a hybrid design with a single DD for the bass, two BA drivers for the mids and one BA driver for the highs.
There is no available information for the driver manufacturer but I guess that they still use their proprietary drivers, designed exclusively for Earsonics.
The Onyx has a 3-way HQ impedance corrector crossover and the engineers have decided to use an extra combination of dampers and passive filters to avoid any unwanted phase shifts.
The internals are encapsulated in a 100% metallic shell with a black mat color.


Build quality and looks

Build quality and finish are excellent, the Onyx seems to be durable and tough enough to handle everyday use with ease, Earsonics professional background is clearly distinguishable here.
The look is minimalistic and industrial, very simple with the Earsonics logo engraved at the center of the shells.


Comfort and isolation

The Onyx is bulkier and heavier than the competition but thanks to the anatomically designed inner surface and the extended nozzle, the fit is actually comfortable and stress-free.
The earpieces fit tightly and stay at place but the weight is an issue and becomes quite noticeable after a while.

Each earpiece has two venting slots but they don’t affect the sound isolation properties and as such the Onyx has pretty good passive noise attenuation.



The cable is detachable with the 2-pin 0.78mm interface ending in a single ended 3.5mm plug.
It is a four core twisted cable with high purity silver and it is of good build quality with extremely low microphonic noise.
A higher quality balanced cable is available as an extra purchase and while I can understand that Earsonics are trying to keep the selling price as low as possible, I would like to see a balanced cable with an adapter or a modular plug cable included in the scope of the delivery.
Competition is fierce and now almost every earphone at this price point comes with a modular cable or an adapter.



ONYX with is 4C-HR cable
1 Cleaning Tool.
2 pairs of comply tips of different sizes.
2 pairs of silicon monoflange tips of different sizes.
2 pairs of silicon bi-flange tips of different sizes.
1 carrying case made from EarSonics.
1 User manual


Power requirements

The Onyx features a nominal impedance of 16.5Ω with a 122dB/mW of sensitivity so it is ridiculously easy to drive but it is heavily susceptible to noise so make sure to use a DAC/amp of the highest quality.
I have used various sources like the FiiO KA3, Violectric Chronos, Cayin RU6 and iBasso DX240 with the included cable and an aftermarket balanced cable by FiiO.


Sound impressions

Earsonics suggested a burn time of about 20-30 hours and thus I did, stretching it to 100 hours.
While fitting the Onyx you must be careful not to squeeze too deep and block the ear tips.
During the fitting process you are going to notice that there is a driver flex which other than making a clicking sound every time you push the shells into your ears, it doesn’t affect the sound properties of the earphone.

The Onyx sounds quite balanced with a mild bass emphasis, combining excellent technical performance with a musical and a warm presentation, a tuning that is rather suitable for all kinds of music and listening habits.

The Onyx is transparent so the DAC/amp and the quality of the listening material should be considered equally important for determining the final audible result.
Onyx is not punishing but not too forgiving either, it will not smooth out bad recordings which nonetheless can be enjoyed as long as you don’t use a very revealing or forward-sounding source.

Sub bass extension is great, it can cover all acoustic instruments with ease while at the same time it is powerful enough to offer plenty of excitement with electronic music without clouding the rest of the frequencies.
The bass is boosted then gently downsloping without giving a pronounced mid – bass hump.
It mostly sounds clear, layered and resolving without affecting mid – range clarity and presence.
The bass stays most of the time controlled and tight, not too slow, recovery is natural but there are quite a few instances that it can sound hollow and boomy.
With simpler one note or pizzicato bass tunes it is good but switching to faster moving and multi-layered bass instruments, then you are going to notice a certain lack of control and a droning effect that gets quite noticeable in symphonic works.


Texture is a nice compromise between being visceral and lean, it sounds quite full and at the same time crispy and well defined, you are not going to miss a single note even at heavily populated bass lines.
The sound is contrasted and muscular, timing is good and the Onyx is not a slouch when it comes to sudden dynamic swings, presenting them with authority and power.

Mid range is crystal clear and well projected with tons of layering and the finest articulation.
Timbre is more or less natural but there is an upper – mid emphasis that is leading to a mildly forward presentation which favors certain tunes.
You can also hear some sharper edges here and there which have an extra bite and can grow into shouting notes.
There is plenty of harmonic wealth and abundance of emotions, voices and instruments sound engaging, full bodied and weighty while the texture is well sculptured with a naturally fading relief.
The mid-range cohesiveness is satisfying and well aligned with the upper bass while smoothly leading to the lower treble.
The Onyx is not strictly a mid – centric earphone but you can certainly tell that the mids sound richer and attract the listener’s attention, especially with female voices as in the following album.


Treble should be considered rather smooth, well controlled and fatigue free yet not lacking in energy and agility.
Open and spacious, it doesn’t sound muted, it is brightly lit, crystal clear and can dive quite deep into the recording to offer some excellent detail retrieval without becoming analytical.
Timbre is mostly natural but you can’t fail to notice an extra shimmering effect and a metallic tone color which is not piercing but it has some traces of acidity that corrupt the sound.
Fading is on the faster side but thankfully not too rushed, instruments are heard naturally, although they tend to lose some of their weight when compared with their lower pitched siblings.


The Onyx is top notch when it comes to instrument positioning with accurate imaging and excellent panning in the horizontal axis but it is not so competent when it comes to depth layering.
The soundstage is well extended with plenty of air, never becoming congested even with large symphonic works while it gets easily adapted to the size of the ensemble, always sounding proportional.

In the end

The Earsonics Onyx is an excellent sounding earphone and a step up from the Corsa.
It is not perfect but a few issues here and there can’t spoil the otherwise great performance, making the Onyx a solid choice and one of the most enjoyable earphones in the mid price category.

Test playlist

Copyright – Laskis Petros 2022.