Kinera Celest Relentless


100+ Head-Fier
Pros: ● Punchy mid-bass
● Lively vocals
● Bright & Extended treble
● Fantastic build quality
● Comfortable, even the size is quite big
● Modular cable
● Nice & practical carrying case
Cons: ● Sub-bass is faint
● Shouty upper mids
● Too bright treble in some tracks
● Non-practical ear tips, considering the price



It seems Kinera has introduced an upgrade to their IEM 'Phoenixcall,' which had a lot of hype in the market for a long time. The Relentless appears to have similar characteristics to the Phoenixcall but with slight new and refined tuning and a different driver configuration. While the Phoenixcall had 1DD+2BA+2 Micro Planar drivers, the Relentless features a 1DD+6BA hybrid driver setup. The BA drivers are customized by Celest, with two BAs for the mid-high frequency band and four for the high frequency band. The DD handles the low and mid-frequency response. These hybrid driver setups tend to produce good sound when tuned properly. Let's dive into the sound section to see how well they've tuned it.


I’m not a fan of V-shaped sound signatures. I’m not into heavy bass; I prefer warm-tuned IEMs like the Ikko OH10 & OH10s, Hidizs MP145, and Aful Explorer. The Kinera Celest Relentless performs well with metal music. It has fast mid-bass, shiny vocals, and a bright treble, but I find the upper region a bit fatiguing during long listening sessions, especially with the stock setup. Changing cables and tips helps a bit, but not much. The Relentless pairs nicely with my Plenue R2 and ifi Hip DAC 2, but with the Moondrop Dawn Pro and Fosi DS1, the upper mids and high frequencies are too shouty. And with Tempo Tec V3, the mids felt a bit congested. I’m a big fan of classic rock music from the 60s, 70s, and 80s, and I didn’t enjoy Relentless as much due to its lack of sub-bass rumble. But it does justice to fast bass tracks from metal bands like Metallica, Megadeth, Iron Maiden, DIO, and Dream Theater.



Kinera was kind enough to send me the Celest Relentless to review. I am not affiliated with the company, and of course, I was not asked for any copy-checking before publishing. All opinions shared in this review are my subjective thoughts.

One thing more: The review is based on my personal experience and what I hear using different sources. Your experience may vary due to personal preference and physical differences like the shape & depth of the ear canal.

For your personal purchase:

Geek Mart is the place if you are in Bangladesh.
Kinera if you live elsewhere.


DAP: Cowon Planue R2, Tempo Tec V3
DAC: Moondrop Dawn Pro, Fossi Audio DS1, ifi Hip DAC 2
Smartphone: POCO X3
Source: Spotify, local hi-res FLAC & DSD files


Driver: 1DD + 6BA
Impedance: 27
Sensitivity: 105 dB
Frequency response: 20Hz-20kHz
Cable: 5N silver plated copper cable
Connector: 0.78mm, 2pin
Cable length: 1.2m (detachable)


● Relentless IEMs
● Carrying case
● Modular cable with 4.4mm & 3.5mm jack
● One set foam tips (S&M) and one set silicon tips (S/M/L)
● Cleaning brush
● Metal bookmark
● Official papers



Unboxing a Kinera IEM in this price range is always a great experience. The box is made of cardboard, and inside, you’ll find the IEMs in a foam cutout along with a premium-looking carrying case that is both sturdy and practical. Although the case is a bit large, it has plenty of space to hold the IEMs, even with a thick cable like the NiceHCK Star Dream. Inside the case, you’ll find a 5N silver-plated copper cable with interchangeable terminals. The package includes 3.5mm SE and 4.4mm balanced terminals. The addition of foam tips along with silicone tips is a nice touch, as many people prefer foam tips for their fit and noise cancellation. There’s also a cleaning brush included, which is very useful if you use the IEMs daily. Overall, the attention to detail is impressive when unboxing the Celest Relentless.







The Kinera Relentless shells are crafted from skin-friendly resin materials, with high-precision ear cavities designed by HeyGears and Celest. The faceplate is hand-painted and features brush strokes depicting the feathers of the relentless bird and the waves of the East China Sea, symbolizing the blend of traditional culture and modern technology. These faceplates are truly pieces of art. The resin shells are slightly larger to accommodate the seven drivers, but they're surprisingly lightweight due to the choice of materials and thoughtful design. Despite being lightweight, they feel sturdy and solid, able to withstand rough use. The stock cable is well-built, well-braided, soft, tangle-free, and made of 5N silver-plated copper. The modular design of the cable is a standout feature. The carrying case is made of leather, giving it a well-finished and premium look. However, the stock ear tips are somewhat disappointing considering the price point.







As I mentioned earlier, the shells of the Relentless are on the larger side, but they are lightweight due to the resin construction. Despite being a bit bulky, the ergonomic design of the shell is excellent, and I feel no pain or discomfort during long listening sessions. My ears are medium-sized, and most of the IEMs I’ve tested and listened to haven’t caused me any fatigue, even the large MP145! However, your experience may vary depending on your ear size, as this is very subjective. The soft cable doesn’t put any pressure on my ears and has no microphonics, even during my morning walks. Personally, I don’t like foam tips as they make my ear canal feel itchy, so I didn’t try them. The supplied silicone ear tips, although soft, are not very comfortable.





A V-shaped tuning right out of the box. There are a lot of audiophiles out there who love this kind of tuning, but it’s not my cup of tea. Unlike other V-shape tuned IEMs, that have a super powerful and bone-cracking rumble in the sub-bass, which is not present here. Furthermore, the sub-bass is a bit weak, in my opinion. Mid-bass has a good body and thump, which is very enjoyable. Vocals, both male and female, have power in them; I think it’s because of the pick in the 8K region. Treble has spark; its shiny and bright. And as a result, sometimes fatiguing.



In Relentless, the sub-bass is there, and you can feel it clearly. The quality of the sub-bass is fantastic and doesn’t bleed to the upper region. The only problem I found is that the quantity is not adequate. In sub-bass heavy tracks like “Raggy Ambassador” by Third World, you will have no problem noticing and feeling the sub-bass. But in tracks like “Hold on My Heart” by Phill Collins, where the bass line is a bit laid back and smooth, you will miss that joy of feeling it. It is a positive point for sub-bass sensitive people, but bad news for listeners like me, who love to enjoy every rumble of sub-bass. With this kind of driver configuration, where a DD is dedicated to handling the lows & mids, I can expect some more sub-bass, right?


The most enjoyable aspect of the Relentless is its ability to reproduce mid-bass like a pro. It captures everything from melodic bass lines to the distinct sounds of kick drums, snares, and toms with bold, authentic character. The slam is so satisfying that you’ll want to keep listening. In tracks like “Master of Puppets” by Metallica, where the mid-bass is fast and intense, the Relentless delivers the entire bass line with the right speed and bold emphasis. The mid-bass is tight and stays in place without overwhelming other frequencies. Metal fans will absolutely love the mid-bass section of the Relentless. However, be aware that the mid-bass can sound boxy in poorly mastered tracks.



The male vocals in Relentless are bold and shiny, not meaty. The midrange is a bit forward, giving the vocals power rather than depth. This might be due to the tuning of the balanced armature (BA) drivers responsible for the mid-high frequencies, even though the Relentless doesn't use low-quality BA drivers. For example, in “Still of the Night” by Whitesnake, David Coverdale's voice lacks its usual thickness and stays bright. On the other hand, Darren Hayes' vocals sound melodic and emotional, shining with brightness and spark. This makes the Relentless great for vocal lovers who enjoy clarity and brightness, but I personally prefer a more laid-back and fuller vocal presentation.


Ah, the true highlight of the Relentless. It produces female vocals with power and amazing clarity, capturing every nuance. While listening to Whitney Houston, known for her high-pitched vocal performance, these IEMs do her tone justice. It feels like she's right in front of me, singing her iconic hit “I Will Always Love You.” I can even hear her breathing between lyrics. However, there’s a downside. During long listening sessions, it can become fatiguing for those who prefer warmth in female vocals rather than brightness. Furthermore, warm and thick vocals like those of Sara Evans or Tanita Tikaram lose their richness due to the shininess in the upper mid-region.



The Relentless does a good job with sound separation, but it's not exceptional. The horizontal separation, or width, is decent. You can clearly hear the left and right channel separation and the placement of different instruments on both sides. However, when the instrument arrangement is complex and heavily layered, it can feel congested, as if all the sounds are coming from one place. In simpler tracks like “Dreams” by Fleetwood Mac, the separation is impressive. You can clearly hear every stroke of the hi-hat, snare, and kick drums, along with McVie’s bass and Lindsey Buckingham’s melodic guitar, without them mixing together. Steve Nicks' vocals are also well-separated throughout the track.


This is what you call treble! It's common in IEMs with a V-shaped sound signature, and the Relentless is no exception. It delivers treble with good extension, rich sparkle, and brightness. Everything you need to hear in the treble section is present. In “Sad but True” by Metallica, those sharp strokes on crash, ride, and bell cymbals are so clear. You can also enjoy Kirk Hammett's high-pitched guitar riffs, which are well separated and create a very melodic environment. However, the downside is that the bright nature of the treble can be fatiguing for someone like me who is sensitive to it. In some treble-heavy tracks from progressive rock or heavy metal bands, the treble can be overly bright, and the sparkle is quite unbearable. But if you are a treble-head or can handle a lot of treble, the Relentless will suit you well.



The soundstage of the Relentless is good and enjoyable, though not particularly wide. You can pinpoint the placement of instruments, even if they are playing the same notes. It feels like a small to medium stage arrangement, with musicians in their own places, but it doesn’t provide a larger or 3D holographic staging. Despite this, it doesn’t feel congested. The lack of sub-bass weight, the forward nature of the midrange, and the shiny treble give the soundstage a spacious feel. In some bass-heavy IEMs, you might miss this sense of space. It's commendable for its clear and well-delivered music, even if the stage isn’t very large.



At first glance, the Relentless might seem like an easy-to-drive IEM since you can use it with your smartphone. But the sound quality from a smartphone alone won’t do it justice. To hear its full potential, you need to power it up with a decent DAC dongle, ideally with a balanced output. Without proper power, the IEM sounds like a lower-budget set with a tiny sound. During my testing with various audio gear, I found that the Relentless has poor synergy with the Tempo Tec V3, producing a muddy midrange without proper instrument separation. And it pairs fantastically with DACs like the ifi Hip DAC 2 and the Cowon Plenue R2 DAP. Be cautious with DACs like the Moondrop Dawn Pro or Fosi Audio DS1, as they can make the upper mids sound shouty.



You’ll definitely need to experiment with different ear tips, as the included ones are quite basic. I tried various tips like Spinfit W1, Omni, CP145, 100+, Divinus Velvet, Dunu S&S, Candy, Tangzu Tan Sanchi, and Penon Liqueur. I ultimately chose the Dunu Candy because it’s comfortable for long listening sessions and adds warmth to the lower frequencies. I didn't change the stock cable since it seemed capable enough to deliver the IEM's original sound. However, a fellow reviewer mentioned that the NiceHCK MixPP cable tames the mid-bass slam (he’s not a fan of thumpy mid-bass) and that the Tangzu Tan Sanchi ear tips can reduce the shouts in the upper mids. So, don’t hesitate to experiment with tips and cables to find a combination that suits your preferences.






● If you are a V-shape sound signature lover
● If you have sub-bass sensitivity
● If you love forward midrange
● If you are a vocal lover
● If you love bright & powerful female vocal
● If you like sparkle in treble
● If you are a metal head
● If you have DAC/AMP, at least a DAC dongle with balanced output.


● If you are a bass-head
● If shouting in mids annoys you
● If power in female vocal creates fatigue
● If you are treble sensitive
● If you don’t like V-shape sound
● If you want warm-tuned IEM with reassessed mids & highs.




The Relentless is a very good IEM, especially if you’re considering it as an upgrade from the Phoenixcall, which is on the brighter side, though the tuning carves of these two are almost the same. Relentless has a refined V-shaped tuning with warm lower part and bright upper part, which has a large fan base. Although it’s not my preferred style, I can’t deny its popularity. Many companies are releasing IEMs with this type of tuning frequently. It may not please everyone, especially those who prefer a warm sound overall or are sensitive to treble, like me. But if you enjoy this kind of tuning or want to upgrade from your current V-type tuning IEM and are willing to spend $170, the Relentless could be a great choice for you.




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Sonic Sleuth

100+ Head-Fier
Review of Kinera Celest Relentless - It's a spicy boi!
Pros: Robust sub-bass with good extension
Punchy and dynamic mid-bass
Wide soundstage
Excellent detail retrieval
Comfortable fit and ergonomic design
Cons: Recessed mid-range can sound unnatural
Slight bass bleed into the lower mids
Treble can be fatiguing and splashy
Lacks overall refinement and balance

I would like to thank @gadgetgod and HiFiGo for sending this unit as part of the review tour.

You can purchase Celest Relentless at the following link (not an affiliate link):

Also, I’m not a seasoned reviewer or a seasoned audiophile, so whatever I say is purely my observations and your results may vary.

I’m not the one to usually focus on specifications and numbers. I focus more on how happy I am with the equipment’s sound and that’s it.

Sources used:
  • xDuoo XD05 Pro (AKM / Rohm) (w/ SS3602 OpAmps)
  • Dita Navigator
  • D16 Taipan
  • Qudelix T-71
  • RME ADI-2 Pro FS R
  • iFi Go Pods

Design of the IEM​

The Relentless features a sleek design with an all-resin shell and a 3D-printed internal acoustic structure. The faceplate, inspired by natural elements, gives it a sophisticated and artistic look. The included cable is modular, allowing easy switching between 3.5mm single-ended and 4.4mm balanced terminations. It's soft, tangle-free, and easy to manage, enhancing the overall usability of the IEMs.


Fit and Comfort of the IEM​

The Relentless is lightweight and fits comfortably in the ear. The wide bore ear tips provided ensure a secure seal, contributing to both comfort and sound isolation. Extended listening sessions are enjoyable without causing fatigue, thanks to the ergonomic design.




Sub Bass​

The sub-bass on the Celest Relentless is robust, delivering a solid foundation for bass-heavy tracks. It extends well, providing that deep, satisfying rumble that bass enthusiasts crave. However, it does tend to bleed into the mid-bass slightly, which can affect the overall clarity.

Mid Bass​

Mid-bass is punchy and dynamic, contributing to the fun and engaging nature of the sound signature. Despite its emphasis, it doesn't overshadow the other frequencies too much but does introduce a slight muddiness into the lower mids.

Mid Range​

The mid-range is where the Celest Relentless shows its V-shaped tuning most prominently. There's a noticeable dip between 500 and 700 Hz, which can make vocals and instruments sound a bit recessed and unnatural. The rise in the upper mids helps to bring some energy back, particularly benefiting female vocals, but the overall mid-range clarity is compromised.


Treble is lively and forward, adding excitement to the sound. There's a good amount of detail and air, though it can verge on being fatiguing for those sensitive to high frequencies. Cymbals and high hats are prominent but can sometimes sound splashy and uncontrolled.

Tone and Timbre​

The tone and timbre of the Relentless are generally pleasing but can sound a bit artificial due to the recessed mid-range. Instruments and vocals sometimes lack the natural warmth and presence found in more neutrally tuned IEMs.

Staging, Instrument Separation, and Layering​

The soundstage is impressively wide for an IEM in this price range, offering a decent sense of space. Instrument separation and layering are competent, allowing for an immersive listening experience. While not exceptional, it performs well enough to keep complex tracks from sounding congested.

Detail Retrieval​

Detail retrieval is one of the strong points of the Relentless. The emphasis on treble brings out micro details and subtle nuances in the music. However, the recessed mid-range can sometimes mask details in that frequency range.


Technically, the Relentless is solid, particularly in terms of detail retrieval and soundstage. It competes well with other IEMs in its price range, though it does fall short of higher-end models in terms of overall refinement and balance.


The Kinera Celest Relentless is a fun and engaging IEM with a strong V-shaped sound signature. While it offers impressive detail retrieval and a wide soundstage, the recessed mid-range and slight bass bleed may not appeal to those looking for a more balanced and natural sound. It's a great option for those who prioritize excitement and energy in their music over neutrality.
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Reactions: ILuvAudio
Excellent review. I was considered this as an upgraded to the Explorer. Seems like I'd have to rethink.


New Head-Fier
Kinera Celest Relentless review of hybrid iem by ICYGENIUS 🎧
Pros: Gorgeous looking headphones
Large set of accessories
Very energetic and lively musical tone
Massive deep and textured bass
Excellent low-frequency transparency and audibility of saturation and distortion
Mids are light and not fatiguing
The transients and attacks of the drums are excellent, I'm surprised by the technique of this set
Treble is super detailed and airy, it's a real abundance
The sound stage has excellent construction and depth that carries you away and immerses you in every musical composition.
Cons: They are really large and stick out a little from the ear, just keep that in mind
High frequencies may be excessive in some songs but it also depends on your music library
- Introduction -
Friends, I welcome you all to icygenius, and today in our review we will look at hybrid headphones from the Celest company.
They come in a small box with an excellent design, there is a company logo, the number of drivers is indicated below, and this new product is called Relentless.


And here there is a QR code to check the originality of the product!

And from the interesting things here written in a story from Chinese fantasy literature «Shan Hai Jing», it tells the story of a girl who tragically drowned while swimming in the East China Sea.
Subsequently, she transformed into a bird, said to be ruthless, and took on the responsibility of protecting other creatures by reclaiming the sea.The design and customization of the headphones are based on this tragic and heroic story of a little girl, which is quite unusual, you will agree.

Therefore, a powerful combination of one dynamic emitter and six reinforcement emitters is responsible for the sound here, and the sensitivity is 105 dB, and they received a 27 ohm impedance.

- Let's take a look at what's included -
1. Excellent branded case for storing headphones

2. Two sets of silicone ear tips, and one set of foam ear tips

3. A good and convenient cable with 2 pin connectors and a modular plug system, you can put both a balanced 4.4 and a regular 3.5 jack here



4. Instructions

5. Headphone cleaning brush

6. Bookmark in the shape of a bird

And here they are, the headphones themselves, made entirely of resin with a very beautiful design of the front panel in the form of sea foam with the inscription Celest on both headphones!

And here is a standard 2-pin connector and a very small hole for compensation.

And since the inside is slightly darkened, we can see those same proprietary Celest armature drivers and a dynamic driver.

And the sound guide here is quite wide with a protective metal mesh on top.
IMG_4594 (1).jpg




And it’s worth saying that the headphones turned out to be quite large, far from miniature, but nevertheless they fit perfectly in the ears, there is no discomfort at all, and they stick out from the ear a little, but the convenience and comfort is excellent, and I used both standard silicone ear tips and others according to the Tangzu Sancai type, I didn’t experience any problems with the fit, as did the flex driver.
- Tuning and Conception -

And now we come to the most important part of the review - an analysis of the sound of the Celest Relentless headphones and starting with their tuning, which is actually not common lately, there is a powerful boost in low frequencies by as much as 12 dB with a neat transition to the mid-frequency region, and after that we see the strengthening of the upper mid area, which is on par with the bass, so don’t worry, these headphones won’t tire you with their presentation, but if there was less bass here, then this balance and this edge of the relationship between low frequencies and upper mids would be lost here here everything is done clearly and correctly compared from the point of view of the approach to tuning headphones, and the high frequencies here surprisingly have very good extension and only very smoothly attenuate at the edge after 15 kHz, which is within the normal range, so the headphones definitely do not sound compressed or dull in this range, but let's look at it in order.
(Low Frequencies)

Low frequencies here are presented as very massive, clearly highlighted in texture, the sub-bass is deep with a good noticeable infra-bass, and the mid-bass has a clear and killer punch and impact, and yet 12 decibels of gain is no joke , which is why the bass in many compositions is presented to us with much more weight and impact than in other headphones, and I’m definitely sure that this amount will be enough for most listeners, unless, of course, you are a super hard basshead for whom 20 decibels of gain will not be enough, but I’m sure there are not many of them here haha.
(Mid Frequencies)
But the mid frequencies here are presented very interestingly they are energetic, not at all tiring, a little lighter in the vocal part due to a small pit, but nevertheless the overall tone of presentation here is pleasant, super airy, energetic but without unnecessary tiring brightness,and the vocals here reveal themselves quite interestingly, that male and female in perception are in some very wide space, slightly coming forward in terms of production, and the drums with very prominent transients and initial attack perfectly complement this overall cheerful and perky tone of delivery, but it’s worth saying that to the neutral dry monitor and which warm side this model definitely does not go to,here we have a cooler transparent tone, which I sometimes even like better and I often miss it, since there are so many warm headphones on the market now, this is just for those who are tired of all these imposing and relaxed presentations, then these guys headphones are what you need to charge yourself, so to speak, and spend time with your favorite compositions,be it heavy metal or something lighter and acoustic, since they reveal all these genres, they are very interesting and I would even say that in their own unique way, these headphones have a certain catchy charm.
(High Frequencies)
But the high frequencies are just a real mountain of airy abundance and demonstrative technicality, and I definitely didn’t expect this, here it is daring analytical tuning and a slightly bright tone of presentation, but without any obvious fatigue , without a crooked reinforcement timbre, and a mountain of sibilants, that is, everything was done here with taste and with a laid down concept that was understandable to everyone, where they adhered to the task of clearly reviving all your compositions, giving
more of a feeling of airy energy and really cool revealed detail of the cymbals and various micro nuances, the analytical side is especially good here, since you can listen and simply analyze your favorite and familiar compositions without any problems, and if you want, you just plug in your headphones and in the evening in a calm atmosphere after a hard day of work, just listen to music that will smoothly take you into this musical stream with a gorgeous sound stage.

My conclusion on this headphones!
Celest Relentless are very interesting headphones with a rather rare but immediately memorable spectacular and energetic sound, there is a textured powerful punchy bass, a transparent smooth midrange, and very detailed and technical high frequencies with a lot of air.
Aliexpress Kinera Official Store:
I will be glad if you subscribe to my YouTube channel and watch this full review on Celest Relentless!

Looks like Kinera following mids like this a lot...


New Head-Fier
Superb Offering by Celest! The Celest Relentless
Pros: 1. Proper V-shape and fun sounding
2. Clean and extensive treble
3. Forward and smooth mid range
4. Satisfying and wholesome bass
Cons: 1. Details and clarity in th upper frequencies

Review Of The Celest Relentless



A sub-brand of the notorious Kinera, Celest is renowned for its exquisitely designed and well-tuned in-ear monitors. And when it comes to their consideration and commitment, Celest is right on par, providing their exquisite IEMs and excellent tuning. I've evaluated a number of Celest IEMs, including their first model, the Gumiho, which received high marks from audiophiles for its distinctive and pleasant tuning. For evaluation reasons, I had the good fortune to obtain their newest flagship IEM, called Relentless. However, before moving on, let me make a few clarifications.



*Since this unit tour was organised by the beautiful people at HiFiGo, I am grateful to them. And as I've said in all of my evaluations, the same is true for this one: all of the concepts I've expressed below are entirely my own, original ideas that haven't been influenced by anyone else. If interested, go to this link.
*I am not associated with the connection, and I receive no financial assistance from anyone.
*For the remainder of the review, I will refer to these IEMs as “Relentless.”
*I am using different Ear-tips for convenience and better versatility.
*Finally, I will only evaluate the Relentless based on their performance, even though I will explain how it feels and seems physically and aesthetically.


The relentless is equipped with a multi-driver hybrid system that includes an 8mm dynamic driver, 4 bespoke 10012 balance armatures handling high frequencies, and 2 unique 29689 balanced armatures handling mid-high frequencies. The shells, which are made of 3D printed resin created by HeyGears and have an ocean-like pattern running across the faceplate. The body of the shell is translucent and has a blue tint. I had no trouble wearing the shells for extended periods of time, and the fit and comfort were fine. The The 5N copper silver-plated cable that is included with the IEMs has interchangeable plug modulation on one side and two-pin connectors on the other.However, the cable's quality seems strange, as though it was manufactured of inferior materials for $200 IEMs. To be exact, I was unable to switch from the 4.4mm to the 3.5mm termination. Additional accessories include two interchangeable plugs (3.5mm and 4.4mm), a travel bag, a selection of eartips, a cleaning brush, and a gorgeous metal bookmark.


***Above Photo Credit***


I discovered when listening to the Relentless that the tuning is in the proper V-shape and that many people would love it because of how distinct and detailed it sounds. Listening to them, I can tell that Celest has struck gold. IEMs in this price bracket sound either highly revealing, adding some noise to the mix that first seems detailed and fascinating but might get harsh and piercing after lengthy listening. Out of all the bright and detailed sounding IEMs in this price range, I think that this well-tuned model with decent control over offensive characteristics being introduced and friendly response it creates is what most people would like. In terms of the treble It is really well-executed with excellent details; the midrange is clear and prominent, and the bass has a powerful, weighty presentation that many people will love. Even if these particular features seem wonderful, I believe that the relentless may not be the right fit if clarity or resolution come to mind. Let's investigate the sound more thoroughly and learn more about it.



The Relentless has one of the best extended trebles in their lineup of IEMs, in my opinion. The treble is greatly extended with good airy and detailed presentation, as the notes become well rounded while the tuning retains the expressive nature of the notes. The treble quality is sufficient to make the sound appealing and vibrant. I believe that the treble and mid range's forwardness makes it possible for the response to sound so fluid and detailed. The vocals and instruments sound transparent and clear, and they sound constant and linear across the response. The high treble is bright and energetic with amazing details. Without adding any sibilance or peakiness, the lower treble introduces more prominent vocalists and instruments with the same liveliness and clarity. Listening to brighter or livelier tracks like ZERO ICHI by Queen Bee features forward-sounding, enticing vocals where the unrefinement in the notes and sibilance does come across noticeably. On the other hand, when I listen to tracks like Spiral by LONGMAN, the vocals and instruments fully grasp over the response and the overall presentation sounds much pronounced and vibrant. As a result, the treble region's overall presentation is vivid, fluid, and well-extended.

Mid Range

Regarding the mid range, I think the forwardness mixed with softness creates an open, airy response; that is, the vocals and instruments sound distinct and well-articulated, but the notes don't sound harsh or shouty even if they are packed with energy. In terms of energy, the upper mid range reverberates with the lower treble, and it generates a forward-thinking and expressive response in terms of presence. While the quality is pretty high, the notes aren't very crisp or well-defined. The vocals and instruments sound clear and vibrant, and the decent separation prevents the mix from becoming too compressed or unrefined. The lower mid range is comparable in that it is a little muted, but the notes' hazy character is still audible. Because the notes' quality isn't completely acknowledged beforehand, their weight and thickness aren't fully appreciated, which leaves the upper mid range lacking in warmth and fullness. Songs like "blan_" by Arika and "When We Die" by YUNGBLUD both have vocals that sound a little too close to being tonally strange because they lack the control over the lower notes, which would have given their voices more body and character. Even the instrumentals sound forward-thinking and energetic, but the individual notes aren't very well defined. The emphasis in the upper mid range, in my opinion, is way more than it should be because it mutes or prevents the lower mid range from coming through. However, there are some tracks with vocals that are surprisingly very neat and captivating, like Ai Higuchi's track Akuma no Ko, which sounds incredibly mesmerizing when left alone. This makes the vocals sound well extended and airier, and it even seems complete with the playful instruments complementing her vocals.


Regarding the bass, it's a really gratifying and wholesome bass that may occasionally become a bit too much at the same time as it's weighty and fulfilling and can occasionally become influential. The mid-bass region is also well-accentuated and sounds meaty and booming, if not forceful or rumbling, but the emphasis is in the sub-bass region, which adds good heaviness and strong presence at the same time. The notes begin to sound boomy at some moments, and the mid bass leaks amount of bass rather than quality, giving the impression that it is not properly controlled. The bass has a lot of intensity and is really well-textured and detailed. Songs like "Hello" by RXPHY have a strong impact from the sub bass to the mid bass, particularly in the 80-200Hz range. The bass drops are audible and have sufficient boom and heft, but the clarity between the notes gets lost in the flow, giving the impression that only one note is being played. This has an influence on other instruments in this range. Particularly the bass guitar, which sounds muted and submerged; this is well exposed in songs like MAN WITH A MISSION's Kizuna No Kiseki. The bass is just incredibly powerful and well-accumulated, which makes the bass response thumping, authoritative, and well-presented overall.

Technical Performance

In terms of technical specifications, the Relentless is on pace, if not better than, IEMs in the same or lower price range. To be honest, I would have liked more from it, but it is undeniably a smoother sounding, enjoyable, and safe sounding IEM. Let's talk about the details.


Soundstage, Sound Imaging & Separation

Although I would have preferred a more distinct and clearer sound, the stage is wide and far enough to create a spacious sound, especially when the vocals are very open, well spread, and exented. With fairly good imaging and separation, I was able to determine positioning and the source of the sound.

Speed & Resolution

Although the Relentless's resolution ability isn't very remarkable, the macro details are easily seen. Although the notes' assault and decay are reasonably metered, they do delay and result in a less ordered and coherent reaction.

Sound Impressions


Sony WM1A - I believe the notes in the high frequencies got more rounded and much more enjoyable to listen to without sacrificing any extension or air while listening to the Relentless with the WM1A. I also found that the response sounded much broader and deeper to add more heft and warmth in the bottom notes. Overall, I think the response is smoother and sounds better than a v-shape.


FiiO M15S - The response from the Relentless with M15S sounded cleaner and crisper than from any other source I tried. The treble became less forward-provoking and the bass became more regulated, resulting in an improvement in the clarity of details and resolution. Though it is not a particularly perceptible improvement, the mid range felt significantly resolved, with singers and instruments sounding stronger in clarity and precision. It sounds really lively and V-shaped, with a more structured bass and crisp mids and treble, but it also has a feeling of clarity and detail.



Millet - Anytime Anywhere
Ai Higuchi - Akuma no Ko
Anri - I can’t stop the loneliness
Kohana Lam - A Few Sentimental
Kohana Lam - Loving Me, Loving You
Uru - Kimino Shiawasewo
Uru - Kamihitoe
Kujira Yumemi - Kenka
Majiko - Kokoronashi
Anly - Sukinishinayo
ZERO ICHI - Queen Bee
Kohama Lam - A Few Sentimental
Kohana Lam - Loving Me, Loving You
Miliyah - Kono Yumega Samerumade
Rokudenashi - The Flame Of Love
Yu-Peng Chen - A New Day with Hope
Yu-Peng Chen - Another Hopeful Tomorrow
Yu-Peng Chen - For Riddles, for Wonders
RXPHY - Hello
Valentino Khan - Satellite
Kai Wachi - Happier By Now
Jawns - Erotica
ISOxo - how2fly
Kai Wachi - Happier By Now
Weeknd - Popular
YUNGBLUD - When We Die(Can We Still Get High)
Bring to Horizon - Kool-Aid
Middle Kids - Bend
FLETCHER - Leads Me On
Loathe - Aggressive Evolution
The Weeknd - Save Your Tears
Sigrid - Burning Bridges
AURORA - Black Water Lilies
AURORA - Runaway
X Ambassadors - Renegades
Lupe Fiasco - Words I Never Said
Macklemore & Ryan Lewis - Can’t Hold Us
Goyte - Somebody That I Used To Know
Jay-Z - Run This Town
Lady Gaga - Poker Face
Lady Gaga - Just Dance
Ladytron - Ghost
Travis - Love Will Come Through
LINKIN PARK - Somewhere I Belong
DJ Shadow - Six Days (Remix)
Hoobastank - The Reason
Ricky Martin - I Don’t Care
Tool - 7empest
Tool - Vicarious
A Flock Of Seagulls - Space Age Love Song
Zack Hemsey - Vengeance
Elton John - I’m Still Standing
The Moody Blues - Nights In White Satin
Micheal Sembello - Maniac
Guns N’ Roses - Sweet Child O’ Mine
A.R. Rahman - Kun Faya Kun


In the conclusion, I believe that the Relentless is the best all-around IEM in terms of smoothness of sound and balance, without sacrificing any detail. In my opinion, Celest's unrelenting IEMs are the best in their lineup; they seem to have perfected the art of tuning. I heartily suggest them to anyone searching for an IEM that isn't bright, sibilant, or lean sounding and that has to sound smooth yet detailed without missing in any response from any part of the frequencies.

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500+ Head-Fier
Celest Relentless - relentlessly V, relentlessly fun
Pros: A tasteful V-shape
Bass can rumble and has serious heft
Vocals are present but not too in your face
A good display of treble microdetails
No major issues timbrally
Fairly priced for the whole package
Pretty, semi-translucent shells
Beautiful packaging and a decent 3.5/4.4 swappable cable
Cons: Not an all arounder
Not the last word in treble airiness
Not the best bass resolution
Could have a more generous soundstage
Slight BA-timbre is both a gift and a curse depending on preference

Having had the possibility to try so many different sets in a relatively short time I felt obliged to go ahead and express my gratitude by trying to help some lost souls out there, just as I was when I first stumbled upon this weird hobby about wired earphones – so yesteryear! … I thought. Possibilities are seemingly endless and only by getting to meet the right people did I manage to jump onboard the train heading the 'right' direction without getting off-track thousands of times along the way. Make sure to understand the helping person's preferences and you too can find your footing and hit the ground running in no time.

A Quick Intermezzo About Me

I won't bore you for too long with personal trivia, however my quick & short background resume goes as follows. Currently I am 27 years old and more in awe of sheer power of music by the day. I have always been moved by music just that slight bit more than average, I'd say. My spending started with a roughly 200€ Bose bluetooth speaker back in my first grade of highschool. What an extraterrestrial thing that was in early 2010s. And it keeps on playing to this day – a true testament of quality. Also sounded fantastic back then, nowadays … yeah, not so much. Lots of BT speakers, TWS, car audio speakers, IEMs, etc., later bring me to this day when I truly consider myself an audiophile. What brings me the most joy beside listening to music is singing, so I am currently participating in a choir and challenging myself with solo vocal covers (check the links in my signature to hear my projects). Unsure where all this leads, but the journey itself is marvelous and life is nothing but a journey.

Disclaimer: I received this unit of Celest Relentless free of charge via Kinera Celest in exchange for a review and I greatly appreciate this opportunity. I am in no way incentivized to speak highly of this set. Should this review tip you over the edge and you decide on this IEM as your next purchase, I welcome you to check it out here: AliExpress Official Store Link

How my reviews are structured

I will start off by mentioning the packaging & accessories, then continue by placing the showcased IEM in my special trademarked graph accompanied with other similarly priced or similar in specs IEMs I own and know well. Then, I sum this part up by giving it a score on certain qualities to help reach the final star score. Beyond that, I will choose a few songs to talk about where I feel the set's downsides and strengths are best conveyed.

Here is the quick and rough description of how I understand various star ratings:
1 star – do not even think about it :star2:
2 stars – it has too many drawbacks and gets demolished by competition :star2::star2:
3 stars – this item has the potential but feels a bit too bland and has multiple issues :star2::star2::star2:
4 stars – wonderful item with rare and mostly subjective drawbacks :star2::star2::star2::star2:
5 stars – wow, it can't possibly get any better :star2::star2::star2::star2::star2:

Keep in mind these ratings are certainly affected by the item's price in the overall assessment too. Sometimes that will result in slightly higher score than based solely on my scoring of bass, midrange, and treble, while other times it results in a slight penalty if I deem the item a tad overpriced.

Important Background About My Listening

As sources I have been using my FiiO BTR7 on high gain and Venture Electronics RA2B-FE + Prime DAC. Certainly no lack of power and quite a different taste on both. Listening was done at a volume ranging between 75-85dB. In this case I am using a Juzear Limpid 4.4 cable and stock orange-grey eartips. I always review with fresh ears – no other IEM gets any ear-time while I am desperately collecting my thoughts regarding the reviewed item.

Packaging & Accessories

Relentless comes in a gorgeous looking box that could be displayed somewhere instead of tucked away in the depths of your drawers.



After admiring and opening the box you are greeted by beautiful faceplates lying alongside a decent feeling case. You also get a solid-feeling and well-behaving cable that has 3.5 and 4.4 swappable terminations and three different sets of eartips. One of these actually worked well for me and I felt no need to tip-roll like crazy.




Such a big part of the overall enjoyment is comfort. I must say these are quite large and that might affect some people's ease of use. They are, however, very light, so keeping them in place is not too difficult. I would advise you to think about all the IEMs you have tried and try to understand the shapes that work and those that do not work. This sort of flat back shape is not my favourite due to my pronounced helical crus deep within my concha. I much prefer a bigger cut-out for the concha. Since the nozzle is decently long, this did not affect me too much.


Let's get going!

Graph & Scores

This trademarked graph I came up with does not come with a thick user manual. All you need to know is that sets further left are warmer than sets further right, and sets higher up are better technically than sets lower down. Those little yellow lines on both axis represent where sets with average technicalities and neutral overall balance lay. I have also added a few previously reviewed single DDs in the form of Kiwi Ears Singolo, TINHiFi T5S, and Simgot EA500 LM to help form a better perception of how the Relentless fares technically and balance-wise vs some well-regarded single DDs.


Here are my scores on the Relentless in individual categories. All three subcategories of each of the frequency spectrums can be rated 1-5. Keep in mind that I am scoring regardless of the price, so cheaper sets getting a 3 in any given subcategory is already good going! I had to approach this in a simplistic manner so to keep it easy to understand and compare sets from all price brackets. I will eventually form them all into a nicely presented table.


Those that are seriously considering a capable multi-BA+DD hybrid that is still on the affordable side of the spectrum ought to read the song examples and comparisons with other sets below too to get as much of a feel on what one could expect. I really try my best to cover a wide variety to paint the sonic picture of the set for as many of you as possible.


I have decided to tackle the part of talking about the IEM itself a bit differently again – still finding the groove to make it as fluent and worthwhile of a read as I can. I will go through the positives and negatives of a few songs. In the end, I will concisely package the overall impression into a shorter paragraph.

Song #1:

Writing's on the Wall by Tom Ball

Starts of creepily with a piano and strings, later joined by a bunch of instruments. Piano seems just a tad thin in note weight meaning it does not carry as much substance as I would have liked. Strings and brass are recognizably BA-ish in a sense that they carry the sharpness which I honestly like more than how some lesser DDs smooth these out too much - it is both a case of tuning and driver choice as well as their implementation to make it sound correct. The epicness of this song is held back a tad by the somewhat restricted soundstage which is not as elyptical nor tall. Those high-pitched ornaments are nicely delivered in a smooth fashion, however some additional up top air could make them magical. His voice has such a rich tone with overtones to die for – this set does it well, but I must say I would prefer his voice to be placed just a bit higher up and more upfront. What ruins it for me here is just too much midbass and low mid bloat that puts a bit of a veil over the whole orchestra.

Song #2:

I’m in Love by Ayo

This song requires a carefully crafted bass – Relentless is just a bit too relentless in its midbass territory which means it is more of a boom than a rumble. That means this song is different than what I’m used to, but 30s in and I adapt. Thankfully there isn’t a great deal going on in the midbass along with the main rhythm. Other participants are kept up in a higher register including her voice. This shows me that female vocals work better than male vocals. Males get caught in that V-shape just a bit more making them sound less convincing. It is an easy-going song which is well-suited to all aspects of Relentless except for the bass.

Song #3:

London Paris Cardiff by Dominic Miller

Gorgeous start to this song. I like just how concrete the low-end is here with the Relentless. It is a tad overdone, sure, but it ends up sounding simply as if they filmed this on a Friday and were ready to party afterwards with the bass dial already turned up and ready to go! Guitar is very soulful and story-telling. So are the hihats, just the right amount of bite despite being very calmly played and recorded from quite far away, it seems. For the ultimate of clarity and resolution this is not the best set to choose in these pieces – bass will take the focus away from the minutae. Relentless is a set I could see used for this sort of genres when that specific mood hits. I very much enjoyed this tune.

Song #4:

Pack your memories by Lils Mackintosh

Fingersnaps, hihats and bass. Yep, this combo works well for an intro. Relentless does all three well. Fingersnaps are quite rich-sounding and linger for a little while. Hihats are spot on while some more crystal clarity could be desired. Bass notes are not as sharply outlined, but it goes together well with slightly shy hihats and those moody fingersnaps! Lils joins and I must say I am impressed again by how the Relentless handles female vocals. Not too soft and warm, while not overreaching into the fame poison at all either. Sibilance won’t happen, while ‘S’ sounds as ‘S’ instead of ‘THS’ on sets that cut the low-treble area too much. Close to perfect for this song.

Song #5:

Cadabra by Undercatt

Ooof that is one big boy wave of bass coming towards my eardrums. And while I listened to most songs at a calmer volume levels and preferred them that way, here the itch to turn it up just a bit was too strong not to oblige. It also levels out much nicer when you’re up into the 90+dB range. Now sure, I would not advise anyone to listen to the whole album this way, but a song here and there won’t hurt! What is life without fun? This must be one of the better renditions of this song too, just a wallop of bass accompanied by all those wild sounds floating around. I am not missing any detail retrieval nor soundstage dimensions to enjoy this one. Mid-point when that bass rejoins after shorter absence, it’s a powerful experience. Now, ultimately I could do with a bit more rumble and less midbass heft, but it’s different and I love it still.

Song #6:

Love Is a Bitch by Two Feet

I have not yet had my vision shaken at a rather ‘low’ volume, but this song and this IEM achieved that. It really does not look like a big bass set on graphs, but here is where that proved to be the case. Basshead set? Not so sure, depends on which sort of bass you’re after. This song rumbles more than it kicks and punches, but yes, this DD … rumble it can. Pinna is done skillfully and allows for rather high-level listening. The rain in the beginning sounds natural and it made me look through my window while writing this review. His voice is much calmer and stays clear of that midrange dip, so it really is not affected by the V-shape much if any at all. What that means is that I really have no flaws to point out here and if this is the sort of music that forms at least a part of your playlist, add the Relentless to your wishlist for a different sort of experience.

Song #7:

Pachelbel Canon by The London Baroque Consort

Okay, so how does it handle classical? Surely, after all that’s been said about the slightly lacking bass and midrange microdetails and a rather healthy (overly so?) midbass presence, it won’t be any good? Not the case. This recording in particular is not too midbass-forward and it allows for BAs to do the work without too much DD intereference with its rumble and unapologetic quantity of bass. Dynamically, it does very well due to its V-shape. Our hearing perception changes drastically with volume, so making sure that energy is maintained and carried throughout even while the piece is in its quieter passaggios is nicely done. So, what ultimately ends up making it just a bit underwhelming is the mediocre soundstage size – those who prefer a more enclosed or personal experience will be more than happy.

To Sum Up The Celest Relentless

To sum up its qualities and try to see who this is for, I would have to say something along the lines of: It is a set of ample bass presence that forms a stage for BAs to dance on. While the bass can get a bit overwhelming and drowns out the detail and finesse, I would have to recommend this set solely to those whose library consists of mostly female vocals and a dose of electronica. Even then, expect a different bass shelf and maybe a little inconsistent playback in the sense of bass doing another thing than the highs. It is, however, certainly unique and deserves a listen when you get the chance!

Thanks for reading and stay wonderful!
I really dig your chart scoring system! Its fun and i like it a lot👍🏻


New Head-Fier
Pros: Sound,bass, quality, detailed sound
Cons: Little small soundstage




The kinera brand comes from Asia and has proven time and time again that progress and new technologies are something worth using. However, their portfolio includes products of three brands. These are Celest audio, Kinera audio and QoA audio. This review will focus on the latest Celest audio product. I cordially invite you to read MatAudiophiles’ observations about CELEST AUDIO RELENTLESS. Currently priced at $169USD, the headphones offer great value for money.

Unboxing and first impressions:
CELEST AUDIO RELENTLESS comes in a nice cardboard box with high-quality printing. Of course, we have references to motifs from Chinese mythology, which is a very interesting idea and I personally think this approach is very successful. The box contains, as always in the case of Celest products, a quite solid set of accessories. Together with CELEST AUDIO RELENTLESS we, of course, receive headphones, which I will get to in a moment, two sets of tips, one dedicated to vocal experiences and one balanced, and one set of foams in sizes S, M, L. There is also a cleaning tool and a hard, solid case. On the cable side, this time we get a solid eight-core cable made of silver-plated copper. What is new is the detachable plug system and the addition of both 3.5mm and 4.4mm plugs to the set. Additionally, we get a beautiful metal bookmark with motifs referring to the legend with which the headphones are associated. I promised that I would come back to the headphones themselves for a moment. This time we get a model completely made of high-quality resin, the front panels of which are hand-painted and resemble sea waves, the part adjacent to the ear is semi-transparent and allows us to look inside. Where we see a dynamic unit responsible for strong and decisive bass, then we have two units of balanced armatures responsible for mid and high tones, and four units of balanced armatures dedicated to ultra high frequencies. It is worth noting here that both the bass speaker and the mid- and high-range units have separate dedicated acoustic channels/audio tubes ensuring a full three-way design. Of course, the headphones are terminated with a classic 2-pin 0.78mm socket without any unnecessary surprises.

Okay, we’ve already discussed the visual layer and design of CELEST AUDIO RELENTLESS, now it’s time to move on to how the headphones themselves sound.
Low tones: The lower band of CELEST AUDIO RELENTLESS is definitely the strong point of these headphones, the strong emphasis on the lower bands gives these headphones an interesting color full of musicality and engages us in listening to music, at the same time, these are not bass headphones, but have only been tuned to give them more mass and more dynamics in the lower registers. This translates into a very weighted and hard-hitting bottom end, which, however, is far from bassy and jamming. Additionally, the headphones in the lower band perfectly control the transmitted music, maintaining impeccable quality and clarity.
Mid tones: It is true that they have been slightly moved back, but not in such a significant way that I would describe their signature as V, but rather a gentle and very transparent U. It is worth noting that the mid tones retain great readability and are extremely engaging. It is true that I would describe the entire tuning of CELEST AUDIO RELENTLESS as darker, and certainly darker than the previous headphones from this manufacturer. At the same time, we will not lack naturalness and emotionality in our music. The sound stage is quite deep, but it is not extended too far to the sides. So here we have a listening room rather than a concert hall. Which in my opinion fits the signature of the headphones themselves very well. CELEST AUDIO RELENTLESS present music in a way that is not tiring and full of details, which I really like.
High tones: This area in CELEST AUDIO RELENTLESS is quite extensive, there is an excellent amount of detail and a natural and very nice presentation. However, people who are sensitive to high tones should take into account that there can be a lot of treble in these headphones. It can also reach the higher registers strongly and show a classic signature for transducers based on balanced armatures. However, it is not unpleasant, at least not for me, but you should remember that the amount of upper parts of the sound is and will be large.
Technical layer: This is the area in which CELEST AUDIO RELENTLESS literally show their potential, showing an above-average level able to compete with much more expensive items on the market. The technology is excellent and far exceeds the price we will have to pay for these headphones.
The scene: As I mentioned, it is closer to intimacy than spectacular. At the same time, we do not feel crowded or squeezed, the instruments themselves are well distributed both in time and space. Of course, most of the soundstage is spread out in depth rather than width, but I prefer headphones with depth rather than those that play flat.

Control: CELEST AUDIO RELENTLESS are theoretically not demanding, but due to the number of drivers used, they benefit significantly from better and more powerful sources.



CELEST AUDIO RELENTLESS are darker and have a smaller soundstage. However, their sound is more pleasant and easier to listen to. We can especially notice this in the case of long and engaging listening sessions. However, if we prefer brighter headphones with a greater focus on exposing details, phoenixcalls may turn out to be an interesting and cheaper alternative.

IDUN 2.0 from Kinera are much more neutral headphones, but also more boring. However, if we are looking for neutrality in sound, they may be a great option. CELEST AUDIO RELENTLESS will have more details and a more entertaining approach to sound, but both pairs of headphones are very interesting and I think they are worth considering.

CELEST AUDIO RELENTLESS are much cheaper headphones, but offer more details, less bass and a narrower sound stage. They have a more even and less entertaining signature. Although both headphones are focused on listening pleasure. However, Volumes are more sub-bass and have more distant vocals. At the same time, they will also have a larger sound stage. Because I personally love my Volume and I really like their tuning, I consider them a bit more engaging, but they are much more expensive headphones, so their advantage should not surprise anyone. Therefore, it all depends on what we are currently looking for and it is worth listening to both models.

CELEST AUDIO RELENTLESS are one of the most interesting headphones under 200 USD. A very solid proposition from Celest Audio. This time the focus was on the classic hybrid design, which resulted not only in great sound, but also in excellent technical performance. CELEST AUDIO RELENTLESS impresses with its well-thought-out tuning, and thanks to its darker tuning, these headphones are perfect for long listening sessions. The overall U-shaped tuning and rather playful sound make them easy to listen to. Only people sensitive to high tones may feel some concerns, but the foams will quickly cope with it. The quality of workmanship and rich accessories fully justify the price of USD 169 and personally I would gladly pay much more for these headphones because in my opinion they are definitely worth it. Even more so, I consider CELEST AUDIO RELENTLESS a well-thought-out and refined product that will bring a lot of joy to people who pay special attention to details and value high technical skills. CELEST AUDIO RELENTLESS also takes full advantage of the best of both technologies used in them, thanks to which we get beautiful and strong bass, thick and detailed mids and strong and detailed high tones.
Have you listened to Fermat ? I would like to know your opinion even if you haven't done exhaustive comparison
No, I did not listen, sorry.
Would be interesting to see how these compare to the Pula PAO2


500+ Head-Fier
Celest Relentless - When fun meets proficiency
Pros: - Full-bodied and textured low-end, lots of details and great treble extension, fun and engaging tuning, nice overall timbre being a Hybrid set (except for a small touch of BA timbre)
- Great imaging and spacious soundstage along with nice instrument separation
They scale well if connected to a proper source with some amplification
- Build quality and design show lots of attention to details
- Thick yet comfortable shells that provide for very nice isolation
- Wide set of tips provided
- Nice cable with modular plug (3.5mm + 4.4mm jacks)
Cons: - Lower mids could be thicker, the treble is pretty bright and there’s a slight touch of BA timbre along with occasional sibilance
- Thick shells won’t be everyone
- They are not hard to drive but having a good source is highly recommended
- Tough competition (planar sets and single DD champs)


Celest (Kinera sub-brand) is expanding its product portfolio with another release named Relentless, which was somehow confused with the Pandamon 2.0 at first before things somehow became clearer thanks to the announcement of the very different driver configuration and the published photos about the two products.
In this review, I’ll dive deep into this set and provide my own impressions on every aspect of the product.

Disclaimer: the Celest Relentless were sent to me by HiFiGO so that I could write an honest review. This review represents my personal opinion on the set, it isn’t a promotional or paid content and I don’t get any revenue from the sales of this product.
At the time of the review, the Celest Relentless were on sale for 169.99$ at


Technical Specifications​

  • Driver Configuration → 1DD + 6BA
  • Impedance → 27 Ω
  • Sensitivity → 105 dB
  • Frequency Response Range → 20Hz-20kHz
  • Cable → 5N copper silver-plated with 0.72mm 2-PIN connectors
  • Plug Type → Modular plug: straight gold plated 3.5mm or 4.4 mm jack connector


The packaging is good looking and rather elegant, and contains:
  • The Celest Relentless
  • The detachable cable with modular plug (so you can use either the 3.5mm jack or the 4.4mm jack)
  • 3 + 3 + 2 pairs of foam tips (S,M)
  • A storage bag
  • A small cleaning/brushing tool
  • User manual

Design, Build Quality, Comfort and Isolation​

The Celest Relentless are pretty big and thick and look amazing thanks to the coloured and refined design of the faceplate. The build quality is great, they are pretty lightweight for the size and the nozzle is neither too long nor too short, sporting a useful nozzle lip (which is good news).



The cable is very good and it also looks durable, even though this is nothing to be surprised by considering the price range.
If there’s a thing that makes this cable great, then it is the modular plug: by unscrewing the 3.5mm jack, one can swap it with the 4.4mm jack included in the box, providing for more versatility if a balanced output is needed/preferred.
Other than this, nothing new: we find the usual chin slider and no microphone control on the cable.



  • DAC: Topping E30
  • AMP: Topping L30, Fiio A3
  • Mobile phones: Samsung Galaxy S7 Edge, Xiaomi Mi A3, Samsung Galaxy S23 Ultra
  • Moondrop May’s DSP cable with PEQ=0
  • Dongle: Apple Type-C dongle, Fosi DS2, Hidizs XO
  • Portable DAPs: Benjie S8/AGPTEK M30B
  • Other sources: Presonus AudioBox iONE, Elgato Wave XLR, KZ AZ10

Do they need an amplifier?
An amplifier is not strictly needed but it’s recommended. The Relentless scale pretty well and pair well with warm sources due to their bright nature.

Sound signature
The Celest Relentless follow a bright V-shaped signature with some treble emphasis and a low-end shelf. If you are looking for a Harman tuned set, you should probably skip this one.

The sub-bass is controlled but it doesn’t rumble a lot: it’s a very clean sub-bass that won’t probably suit the average basshead’s tastes, but every other listener will not find it lacking. The focus is on the midbass, even though this is not super emphasized either: it has good textures, good punch and nice speed, but the combination between the controlled sub-bass and the emphasized treble makes it a bit less forward than it looks on graphs.
Overall it’s a well done low-end for most genres, but those looking for the most punchy and full bodied bass out there will probably need to keep searching.

The mids are recessed, so those who are on the market for a mid-centric IEM should probably look elsewhere.
The leaner-than-average midbass sometimes struggles to give more warmth and depth to male vocals, although most of the time they still sound nice (yet not really “natural”). The upper midrange is instead forward (at the right point) and somewhat intense, with energetic female vocals and rich violins/electric guitar notes, even though some episodes of sibilance may occur if the tracks are prone to that (this is because of the combination between the upper midrange glare, a slight dip and then a treble boost).
The instruments are generally well separated, the layering is good and it really seems like the Relentless are not afraid of busy and crowded tracks, except for some cases.

The highs are bright and pack a lot of details, and the treble emphasis provides for a very open sound even though this also means that the Relentless should be avoided by those who are sensitive to treble.
For sure, this is one of the IEMs that shine in the treble extension under 200$ (hands down) even though for some genres this may also be a hit or miss because of some particular sounds (i.e. if you listen to a lot of metal, some cymbals may be somewhat aggressive for prolonged use) and for a touch of BA timbre.

The soundstage is pretty wide and has good depth although height is just average. The imaging is very good, with instruments being well pinpointed and separated, this also thanks to the very good treble extension.

How the stock tips impact the sound signature:
  • Celest 221 Vocal Eartips (black): more emphasized treble, airier vocals and instruments, more sibilance
  • Celest 608 Balanced (Red): more balanced, a bit less airy and slightly bassier but less fatiguing than the 221
  • Foam tips: best balance between treble, bass impact and vocals and there is also less sibilance than on 608 and 221. Probably the best choice of the set.

Some comparisons:

Celest Relentless vs Simgot EM6L
Price is quite different yet both are hybrids placed between 100$ and 200$.
The Relentless have a more robust and more textured the low-end (especially in the midbass region), whereas the EM6L have a richer midrange and more natural male vocals; female vocals, instead, sound more detailed and energetic on the Relentless yet a bit more natural and intimate on the EM6L. Both are kinda bright on top but the treble extension is better on the Relentless, even though the EM6L provide for a slightly smoother transition between the upper midrange and the lower midrange (with less occasions of sibilance).
The timbre is nice on both but the EM6L sound a bit more natural, while the Relentless are less accurate from a timbrical perspective yet more fun and technical to listen to, with slightly better instrument separation and a more expansive soundstage. The imaging is not that different and the EM6L compete pretty well in this regard, even though the Relentless have more space to place everything properly and feels more “holographic”.
When it comes to the build quality, accessories, cable and isolation, it’s an easy win for the Relentless, even though the smaller size of the EM6L may be better for some people out there.

Celest Relentless vs Celest Phoenixcall
Different driver configuration yet same company and similar price bracket: ok, let’s do it.
The Relentless are brighter but they somehow feel less “thin” in the treble and sound more appealing and “correct” from a timbrical standpoint. In fact, the sub-bass extension is better on the Relentless and provides for a fuller and more engaging sound. The midbass is very good on both sets but the Relentless have better bass textures and better body, whereas the Phoenixcall compete with slightly faster transients when it comes to rapid basslines. The midrange is recessed on both sets but the Relentless do better in terms of vocals: the fuller low-end makes sure that male vocals don’t disappear and the smoother upper midrange emphasis gives more body and energy to female vocals (they sounded thinner and less natural on the Phoenixcall due to the earlier emphasis followed by a dip). The detail retrieval is very good on both sets too, but the Relentless are more proficient and pack a better treble extension (they also cost more, so it was expected).
Soundstage is wider and deeper on the Relentless, whereas the height is similar. Imaging is better on the Relentless.
The Relentless come with a slightly more versatile cable, but when it comes to build quality, isolation and comfort, they are comparable (even though the smaller and more unique shells of the Phoenixcall will appeal to more people).

Celest Relentless vs Simgot EA1000
Not really fair to compare a hybrid setup with a single DD set, but let’s try anyway.
In terms of timbre/tonality, bass body/depth and vocals, there’s no competition: the EA1000 just sound like a more mature set.
From a technical perspective, though, the Relentless compete quite well: the sub-bass has better extension, the bass is very speedy and it’s well textured (yet not as full bodied as on the EA1000), there’s lots of detail, the treble extension is very good (eveN though slightly less natural than on the EA1000) and both imaging and soundstage are slightly more clinical than on the EA1000.
It’s unfair to compare these since the EA1000 avoid any incoherence that could come from the usage of different drivers, but it’s also true that the Relentless is not getting completely destroyed (which is good news). I would still pick the EA1000 hands down (it’s a more natural set with much better bass quality, richer mids and they also have that effortless way to reproduce every track correctly) but the Relentless really show Celest’s ability to keep up with proficient driver implementations. Anyways, the target is slightly different: those who want a single DD IEM will still pick a single DD IEM and those who search for a hybrid will only want that.
When it comes to cable, accessories and isolation, the Relentless win hands down, whereas the EA1000 look like a slightly more premium set and come in a smaller-sized shell.

Final Thoughts​

After the so-so Pandamon 2.0, Celest managed to score a very nice goal.
The Relentless are yet another proof that Celest knows how to properly fit and implement different drivers without actually killing the overall cohesiveness. For sure, there is still room for improvement (i.e. the occasional sibilance and the slight touch of BA timbre), but the overall sound is pleasant and smooth for a hybrid configuration and the technical performance is up to the expectations for a 150$-200$ hybrid set.
It will be hard to recommend these to those who don’t like bright IEMs or V-shaped tunings, but except for those people everyone else will find the Relentless a fun and technically proficient IEM that will provide for very engaging and musical listening sessions.
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They look something like a Japanese Painting , wow
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Yea definitely. Stunning faceplate.


New Head-Fier
Celest Relentless a well done V shape
Pros: Pros:
Fun and all-rounder sound
Comfortable and Gorgeous-looking shells
A generous amount of accessories
Neat looking modular cable
Excellent Technical Performance
Natural sounding Vocals
Cons: Cons:
Slightly recessed vocals (preference)
Not the easiest to drive
Occasionally bright treble
Despite being in the hobby for years I'm quite new to reviewing so please take my review with a pinch of salt. I do simple and concise reviews for both audio listening and gaming. I listen mostly to KPOP and JPOP. I mainly play Apex Legends and sometimes Valorant for shooter games. Special thanks to HiFiGo for allowing me to review this unit. Here's my short review of the Celest Relentless.

Celest has done it again, pushing the "non-mainstream" sound signature below the 200 USD price point. The Relentless retails at 169 USD and offers a V-shaped tuning. V-shaped IEMs are known to have midbass bleed due to the boost in the lower frequencies but with the Relentless you won't have the same problem. Offering a good bass both in quality and quantity. Great technical performance despite the fun and engaging tuning. The Celest Relentless is for someone who wants to enjoy a V-shaped sound signature without sacrificing the vocal quality.

Fun and all-rounder sound
Comfortable and Gorgeous-looking shells
A generous amount of accessories
Neat looking modular cable
Excellent Technical Performance
Natural sounding Vocals

Slightly recessed vocals (preference)
Not the easiest to drive
Occasionally bright treble

Bass (4.5/5):
The Celest Relentless is a mid-bass focused iem which I usually do not prefer but since the bass quality here is good I found myself enjoying these a lot. A good amount of bass that's enough for an enjoyable listen but probably not basshead level. The bass quality here is well done, it does not slouch on fast-paced tracks nor does it bleed into the mids. A really satisfying all-rounder bass experience for me. My only nitpick would be I would've preferred a bit more sub-bass rumble it may not be lacking but it's just my preference.

Mid Range (4/5):
The midrange here has a very good balance of clarity and weight. V-shaped iems tend to sound muddy in this department but with the relentless, it is safe to say that these have none or a very minimum amount of it. Instruments in the mid-range sound natural and quite detailed. Male vocals sound a bit laid back but has a good texture and never sounded thin despite the clarity. Female vocals are a bit recessed for my preference. Despite that, I was still able to enjoy it a lot because it sounded natural despite the sound signature. Knowing that this is a V-shaped IEM the mid-range here has impressed me a lot it may not align with my preference but I was able to appreciate and like it.

Treble (4/5):
The treble is airy and sparkly but has an occasional hint of peakiness. This was present on the stock silicone tips but with foams or the Divinus Velvet, I haven't experienced the said problem. The treble is very well extended and detailed. Effortlessly detailed without sounding unnatural. The amount of air it gives contributed a lot the the spacious and open-sounding stage.

Technical Performance (5/5):
This is the part that surprised me a lot. As per experience, V-shaped IEMs tend to sacrifice the technical performance due to the boost in the bass but here it offers an excellent amount of details, above-average imaging, and separation. It may not sound the widest but it has a good sense of height and depth while allowing a good separation and space between each instrument and a sense of immersion.

Gaming (5/5):
Does really well both in FPS games and open world. Due to the excellent techs the imaging here is good enough for FPS games and never sounded claustrophobic despite the bass boost. Open world games are really immersive with really good micro details where you can hear the river water flows or the birds chirping.

Overall the Celest Relentless is a keeper IEM for me. Offers a fun all-rounder sound with excellent technical performance and is priced really competitively. I do hope this IEM gets the attention it deserves. It's high on the list of IEMs I would want to purchase if I get the chance. But I do have to say these aren't for the treble-sensitive people you can easily fix that with foams or the Divinus Velvet but if you do not like foam tips and would not want to spend another extra for the specified tips I would recommend you should at least give it a demo first.


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So thankful for the Gaming Performance review, I need to include this in my reviews as well


500+ Head-Fier
Celest Relentless Review
Pros: -Nice all-resin build

-Design is just as gorgeous as it is unique


-Great modular cable

-Nice slight V-shaped sound signature

-Deep, full and punchy bass region

-Resolute and Clean midrange

-Airy & open treble region

-Detail Retrieval


Cons: -Treble brightness may be too much for some

-Bass presence may be a bit too heavy for some hobbyists

-Some sibilance rears its ugly head from time to time

Celest Relentless Review



Celest Relentless


I'm happy to report on this latest iem from Celest Audio which goes by the name of Celest Relentless. I have been very fond of Celest over the last couple years. Ever since the Celest Gumiho I have been a fan. Of course, Celest is also a sister brand of two wildly popular brands in Kinera and Queen of Audio (QOA). So, it stands to reason that I’d enjoy Celest as I’m a huge fan of Kinera and QOA. The lineage is certainly there except Celest is marketed a bit more on the budget side. At any rate, I’ve reviewed many Kinera/Celest/QOA iems in the past and have yet to give a less than stellar review. However, as far as Celest goes, I’ve reviewed the Celest Wyvern Pro (Wyvern Pro Review), Celest Pandamon (Pandamon Review), Celest Pandamon 2.0 (Pandamon 2.0 Review), and the Celest Phoenixcall (Phoenixcall Review) and each one seemed to punch above its price, to a degree at least. Each is built well enough, designed nicely, and each has a unique recognizably distinct character to their sound.


As I said, Celest is really another arm of Kinera and geared more towards the budget sector. Though I have a hard time thinking of Celest in this way due to the obvious quality of their products. I feel any brand which sits under the Kinera umbrella exudes quality through and through and does so in a very economical way for hobbyists like me and many others. The fact that you’re getting the Kinera/QOA expertise with Celest is very comforting. Like I said, ever since the Gumiho Celest hasn’t stopped producing competitive products. So, naturally I was very intrigued by the Relentless. Furthermore, the fact that we can get a 1DD/6BA hybrid set under $200 is also very intriguing for me.


The name Relentless comes from the same classic Chinese tale as previous Celest earphones. That tale is called the “Classic of the Mountains and the Sea”, also known as “Shan Hai”. Like any other Kinera/QOA/Celest product there is a theme which serves as the inspiration behind them. Relentless’ origins are from the tale of Lass, who unfortunately drowned while swimming in the East China Sea. In the wake of this tragic event, she actually turns into a bird named Relentless. Relentless was heroically driven to make sure that such a fate would never transpire in anyone else’s life. Thus, Relentless sets out to reclaim the sea. This name and attachment to this bird actually holds strong meaning in Chinese culture and has become somewhat of a cultural symbol. Relentless represents something that we should all try to emulate as this bird symbolizes “strength, bravery, and unwavering efforts” (per the provided booklet). It also speaks on the fact that the bird “Relentless” has become one of the sacred birds in Ancient China. Not only does this bird represent character traits that we should all try our best to pursue, but this bird is also said to have supernatural powers to foretell fortune or misfortune and bring upon revelation as well as inspiration.


Obviously, there is quite a bit more to the story and I really don’t want to butcher it (which I’m quite positive that I just did). However, I find it completely charming and creative that Celest derives the heart of their products in such a manner. The entire theme of the Relentless is based around this beautiful tale, from the build, design and on down to the tuning. Friends, to put this much care and careful thought into anything brings a whole new appreciation from someone like me. I love trying to find out how the story itself correlates with the set I’m reviewing. Of course, the only brands which go this route is Kinera/QOA/Celest. I couldn’t be more of a fan of this method. Again, it’s unique, creative, profoundly thoughtful and I am all for it. Relentless is a great name and the idea behind this name is wonderful. Nice job Celest!
Well folks, the Relentless has a whole host of fantastic iems within its price point that it will ultimately battle against. Too many to name in this intro paragraph but I think we can all agree that the battle is uphill. Of course, I don’t doubt that Celest has put all of their efforts into crafting a fine set and I intend to find out over very long listening sessions. I’ve had about an hour of initial listening, but we all know that real critical listening happens in a quiet place with no real distractions, I can’t wait. Okay, now that all of this has been said I will put the Relentless on the burn-in station and give it about five days. I’ll see you all in about a week or two folks. The Celest Relentless everyone…

Non-Affiliated Purchasing Links:

Amazon US
I received the Celest Relentless from HiFiGo as a review sample and in exchange I will conduct a full review and feature at I have not received any payment or any other form of compensation for this review. This set is a review sample iem. HiFiGo has not requested to pre-read any review and doesn’t have any control over “what” or “when” anything gets published to All thoughts within this review are my own, though please take note that I will always have my own biases. This is impossible to get around. I try to be as objective as my subjective self can be, but this is an opinion piece folks. Thank you to HiFiGo and thanks for reading.


Ifi Go Blu / Aful SnowyNight / Shanling M6 Ultra / Fiio Q15 / iBasso DX240 / Hidizs S8 Pro / EPZ TP50

Gear used for testing

-Ifi Go Blu


-Hidizs S8 Pro Robin

-Aful SnowyNight

-Fiio Q15

-iBasso DX240 with Amp8 MK2

-Shanling M6 Ultra


Packaging / Accessories


CR Bookmark

One thing that you can be sure of is that Celest is going to try to impress with the unboxing experience. This has been my experience with every Celest branded iem to date and there’s no change with the Relentless’ packaging in front of me now. Truly one of the best designed boxes that I’ve had the pleasure of opening in this price point. The box that the Relentless arrives in is beautiful on its own. There’s a picture of the bird Relentless on the front flying over the swirling and whipping sea with what appears to be a destination in mind. You’ll notice some specs on the back of the box along with a brief explanation of the theme of the Relentless. Once you open the box you’ll be greeted by the Relentless sitting pretty in some foam cut-outs. Next to the Relentless is a very slick looking carrying case. Inside the carrying case you’ll find the cable, modular cable connections, iem cleaning tool, small brush, as well as many eartips. You’ll also spot a box under the Relentless which houses a beautiful looking bookmark that has a picture of Relentless on the front. Similar to what Celest provided for the Pandamon box. Folks I desperately undersold how nice this presentation is. Having an elegant and visually pleasing unboxing is something that I’ve grown accustomed to with this brand.

CR Unboxing
CR Unboxing
CR Unboxing


CR Eartips

Not every brand provides actual quality eartips. This is a constant problem. Most brand will simply throw some tips in the package whether they make sense to the earphone or not. Usually, I am complaining about the quality of the tips. Celest does the opposite. They actually provide eight pairs of tips in total. You get three pairs (S, M L) of the gray colored “Celest 221 vocal tips”. These tips are shallow fit wide bore eartips which do enhance the upper midrange as well as bring upon a sense of air to the sound, to a greater degree anyways. The next set of three (S, M, L) is the “Celest 608 balanced tips” which are almost identical to the old school Fiio Bass tips or the KBear 07 tips. Same sturdy & rigid stem, same rigid flange, not flimsy at all and the bore is also semi-wide like the 07’s. These tips are my personal preference. The last set of two tips (M, L) are some nice slow-rise foam tips. I don’t particularly like foam tips but the included foamies are of good quality and they certainly do knock down the upper mids to a degree as well as cut back the treble a bit. I found the 608 tips work best for me, just for sealing purposes but each set of tips are fine quality.

Carrying case

CR Case

The case that you’ll receive in the packaging is a very nicely fashioned black zipper case covered in almost a harder fabric. I really don’t know the material they used but it’s very nice. This is one of the better made cases that I’ve received with any earphones around this price point. Hands down. The zipper works well. There’s just enough room for the Relentless, the cable, and maybe some extra tips. It isn’t the largest case, but it is slick looking. You’ll notice in the middle of the case that they added the name “Celest”. It’s a nice touch. I rarely use cases, but I will find a use for this one.


CR Cable

Now we get to one of my favorite items that Celest has ever given out. The included cable is very nice. I love a fatter cable and the wire included in the Relentless packaging has a very nice thickness. It’s a white tightly braided 8-core cable with 48 strands. That’s 5N Copper with a silver plating. However, the best part about this cable is in its modular connections. The Relentless comes with both 3.5 single ended and 4.4 balanced modular connectors. However, it’s the way they screw on which is pretty great. You simply line up the pins, push them in and then screw on the jack sleeve which has threads on the inside which screws on tight. It’s a genius way to make sure that your modular Jack’s never fall off. Of course, we’ve seen this style of connection many times in the past, but I do like the implementation on this cable. It feels very secure and doesn’t appear there is a modular jack there. Very nice. All of the fittings on the cable are made of what appears to be stainless steel as well. I have no need to cable swap or upgrade which is very nice for a change.

CR Cable
Celest adds in a very nice cable within the packaging


Build / Design / Internals / Fit

Build Quality

The build is very nice and on part with the price point I’d say. The Relentless is an all-resin earphone with smooth edges and very clean in appearance. Though, it’s true that you can find very good all resin builds at much cheaper costs. However, for this build, Celest actually employed “HeyGears” to craft the 3D printed resin shell. HeyGears is a huge 3D printing service which you’ll notice some brands use from time to time. Namely Letshuoer as well as a few others. So yes, the shell is exquisite from the front to back. No blemishes and the feel of the Relentless is very durable. Please trust me that I have many all-resin sets which don’t exactly exude confidence in their durability over time. Or even just a short drop. Beyond durability, the Relentless is also very light. Weighing in at only 6 grams each earphone the Relentless feel like nothing in the ear. The nozzles are medium length, and they are just over 6mm in width at the nozzle end.

CR Build
CR Build
CR Build
CR Build
CR Build


This is one area where the Relentless absolutely excels. The design is wonderful on this iem folks. One thing that Kinera prides themselves on is design and aesthetic. Naturally this pride has trickled down to Celest as every set I’ve reviewed and spent time with has been very well designed. I’m telling you, when it comes to straight up artisanship, I feel that Kinera/QOA/Celest are some of the best in the business. The Relentless shells are a transparent dark green, so dark it’s difficult to even make out that it is in fact dark green. Yet still transparent enough to allow me to see the inner workings fairly easily, especially when put up to the light. Everything internally is very well put together. I’ve always been a fan of transparent housings and it’s nice to see that on this set. To add to that, the faceplates are where I am inspired to muster words like exquisite, elegant, striking and any other word describing something appealing to the eye. The faceplates have this dark blue hue but with splashes of light blues, whites, and almost an indigo. These waves splashing is hand painted by skilled artists, made to depict waves being tossed around while the overall shape is supposed to represent the feathers of Relentless. I love the correlations of the hand painted design and the overarching theme of the Relentless. Truly a beautiful look. Here’s my round of applause. Please give those who participated in the design a huge pat on the back.


Now, internally Celest decided to pack a very large number of drivers within the Shells of the Relentless. To be exact, they went with one customized 8mm dynamic driver which will control the low to mid frequencies. I don’t know the exact material of the driver at this time. For the upper-mids to highs, Celest decided to use two customized 29689 balanced armature drivers. They also used four 10012 balanced armature drivers which will be responsible for the rest of the treble frequencies. It is blatantly obvious that these drivers are of good quality friends. I never get odd distortions, even at higher volumes. I don’t hear these drivers begin to lose their edge or lose control.


As far as fit is concerned, I don’t know how helpful it is to you for me to explain how the Relentless fits me. Despite that, I must say that the Relentless fits me absolutely perfectly. Of course, most iems fit me very well. Still, the Relentless just seems to be the perfect size, perfect length of nozzle and perfect shape for my ears. I have to assume that most ears will be perfect for this set too. They don’t have any weird angles and they aren’t overly convex where the shell meets the ear. They simply fit very well. To add to that, I also have very good isolation. I’d say better than average for sure. Not enough to compete with ANC earphones but the passive noise isolation is very good.


The Relentless and the Fiio Q15 combine to really create a nice sound.


The Celest Relentless is rated with an impedance of 27 ohms and a sensitivity of 105 db’s. Those numbers translate to… this is a pretty easy set to drive from most any source. Of course, there are iems rated similarly that took less volume steps to equal volume levels. Having said that, the Relentless is easy enough to drive for a nice listening session. I always try out my sets straight from my iPad and the Relentless had plenty of headroom with that so, take that for what you will. Basically, if you have a simple smartphone with a 3.5 single ended jack you’ll be in business. Now, the Relentless certainly scales with a touch more amping power and definitely scales to the quality of any source. As one would expect. I don’t think you need anything crazy to drive this set.

Mobile Listening

The Hidizs S8 Pro is great with this set.
Using the IFi Go Blu I found that it had plenty of dynamics, plenty of volume too. Especially using the 4.4 connection. However, I didn’t really enjoy the pairing. I found that sibilance was an issue for whatever reason with this pairing. More-so than others anyways. Not horrible by any stretch. I found a better match listening with the Qudelix 5k. For Bluetooth sources that is. As for dongle dacs, I chose to use the brand new Hidizs S8 Pro Robin (Review soon) and the pair was very nice. Tonalities contrasted each other very nicely. The same can be said of the EPZ TP50. In fact, I love the TP50 and the Relentless. Dynamics are in abundance and the technical stuff (details, separation, Imaging) are heightened a bit. Using the Aful SnowyNight was the cleanest version of the sound where dongle dacs are concerned. A little less colored but highly resolving.

More juice

Listening with the Fiio Q15 on high gain with the 4.4 balanced connection I found the Relentless took to it very well. In fact, I could say the same for any of my more talented source devices. Whether it was the Q15, iBasso DX240 or Shanling M6 Ultra, each provided me with a nice version of the Relentless tuning. The DX240 showed a bit more sibilance and so I probably was less fond of that device paired with the Relentless, but a good listen. However, out of all of them I certainly enjoyed the velvet sound of the M6 Ultra the most. Just a great listening session every time.

What do you need?

To bring out the dynamics and high-volume ceiling, I’d say try to get a nice dongle dac. Preferably a slightly warmer to warm/neutral source (not a requirement). The Relentless most certainly does sound much better from a better source with a bit more power and so if you can get your hands on something of decent quality the Relentless will reward you for it. However, if all you can afford is the Relentless and the Relentless alone then you can make do with a simple phone.


Sound Impressions

Note: I want to preface this section by stating that I did give the Relentless roughly 50 hours of “run-in” prior to critically assessing them. I listen to all reviews using flac or better files which are stored on my devices. The majority of my listening is with UAPP (USB Audio Player Pro), though at times I will use Hiby Player and for most Bluetooth listening I will use Poweramp (the best looking & functioning audio app).

I find the Relentless to be a V-shaped iem with a slightly brighter hue up top. I hear a crisper sound toward the top half and a smoother sound towards the bottom half of the mix. One thing which is nice to hear is the nice cohesion of all of the drivers. I don’t hear anything off and there’s good transitions between each 3rd of the mix (bass to mids, mids to treble). Also, I said this is a brighter sound but that isn’t always the case. It really depends on the track you are listening to. The lower half is warmer and does contrast the treble quite well. So, take that first sentence with a grain of salt. It isn’t overtly or overly bright at all. At least not to my ears. Maybe for someone who is very sensitive to treble it will be an issue but to the average listener this is just a well-done V-shaped hybrid iem.

Condensed Sound Between the 20’s

Note: I add this section in for the express purpose of providing the reader with an ultra-condensed version of my review where I usually highlight some of the better attributes of the set I’m reviewing. I understand that not everyone wants to read my mindless babble for too long.

Each 3rd of the mix

You certainly have a rise in the bass region with a slight tilt toward the mid-bass. Though there really isn’t a huge disparity between the sub & mid-bass. The sub-bass region can get pretty deep in pitch when called upon though. There’s certainly no lack of rumble here. The mid-bass can BANG. Celest did a nice job of adding emphasis without congesting the sound or adding veil across the mix. Just enough to add some decent thunder, grumble, and boom down low. There’s a nice downward glide from the bass to the mids adding some warmth in that region. The midrange does have a hint of recession but that’s to be expected. I don’t find the sound in the midrange to be too pushed back. In fact, I feel the midrange I’d well highlighted and vocals aren’t lost on me. It’s a nice midrange. Open, airy, detailed, yet not too thin. Upper mids have more sparkle and they are more forward which is great for female vocalists. The treble is airy, very open sounding with good space between instruments. Perhaps a hair smoother than it is crisp but still nicely detailed. Extension is very nice as well. The Relentless has good separation across the mix, better than average detail retrieval and very nice imaging for the price. I hear an average sized stage with decent depth of field as well. Celest did a nice job tuning this set.

Graph courtesy of Jaytiss, Thanks!

I could put this set anywhere and it would be photogenic.

Bass Region

The low end has some heft to it! No this isn’t a basshead iem, but boy can it bang! The low-end has a wonderfully controlled slam and a deeply extended sub-bass which is at a very nice level against the rest of the spectrum. To be honest, I think the low-end is my favorite aspect of the Relentless. I love that Celest tuned the Relentless to go right to the brink of too much with their emphasis in this region. Enough to hit hard and give me that resonant rumble but not so much to create veil or become muddy. This is a nicely tight bass for the quantity. In fact, for a dynamic driver I don’t think you can get much more transient swift. Notes are dense, contoured, textured very well and have very nice impact. Attack has that concrete solidity at the attack as the crest of each note offers a clean initial snap. Decay has the slightest bit of atmospheric lag but not even close to slow. No sir. This is a well-defined low-end that (in my opinion) can take on the best in its price point (at least that I’ve heard). I find the bass to be very dexterous with an almost ductile ability to take on complicated bass passages. It’s a nice one folks.


Like I said, the bass goes pretty deep in pitch and as it does the Relentless is able to give a nice level of dense rumble. I am able to feel the lowest of lows quite easily. The sub-bass seems to offer that tactile and vibratory physical recognition as it has a haptic ability to portray deeper notes. Is this the deepest sub-bass in the price point? No, it isn’t. There are sets which can reach deeper. However, there aren’t many iems between $150 and $200 which can maneuver around with the same agility all the while staying pronounced and bold. Again, not basshead. Let’s get that clear. This is a clean and well-defined bass that is north of moderate and can rumble enough to make any track fun. Bass guitar has that grumbling, gravely, and altogether guttural reverberant growl. Yet it won’t cover over any other area of the mix, unless the track you are listening to is recorded that way. At which point, that’d be a good thing. I can feel the bass drop in “2040” by Lil Durk & Lil Baby. It’s tight, it’s robust and it’s authoritative. “Put On” by Jeezy is an awesome track to test for bass speed as it is recorded with a bass line that reaches past 300 beats per minute. The Relentless laughs at this track as it does nothing to trip it up. I hear each note, attack through release, clean tight and defined with obvious depth of bass. It’s nice.


Moving onto the mid-bass is another spotlight in my opinion. I love me some good bass. Always have. Every set I get the first thing I test is the bass. The first track I played was “Start the Machine” by Angels & Airwaves. The bass isn’t soft at all as the Relentless takes this slightly distorted bassline with very good precision. Not quite balanced armature definition, but a more organic and atmospheric dynamic driver sound that has meat to it and great timbre. Another track that is very nice on this set is “Use Me Up” by Lake Street Dive. It shows off two simultaneous bass lines and one being a deep bass guitar. I love how full and rigid they both come across. I can hear the changes in tempo and the clean rebound each note makes. The sound is very nice folks. It’s deep, full, and convex with plenty of speed per the quantity. I don’t want to oversell what I’m hearing but also, I want you to know what I hear from my perspective. I enjoy the level of bass, where it transitions into the midrange, and I enjoy the texture of the bass. It isn’t wooly, pillowy, bloated, or one-noted. The bass isn’t flat, anemic or dry either. It’s full, but also adept at maneuvering around fairly complicated sections of music. For sure the amount of mid-bass convexity will not be to everyone’s liking. On the flip, bassheads may yearn for a bit more. The Relentless seems to sit right in the middle of not enough and too much and for what it’s worth… It sounds damn good.

Downsides to the Bass Region

I don’t have many downsides to list here. For the price and against the competition I feel the bass is pretty nice. However, there will be those who think I’m nuts about this. Those people would likely be bassheads who desperately want to bob their heads to a much more bulbous sound. Also, those who love a flatter bass, less intrusion into the midrange, less rumble may also find the Relentless doesn’t live up to their standards.

To me the bass is probably my favorite area of the mix. It does so many things very well. Full and weighted bass guitars, booming kick-drums, great for synth bass and I love a good bass boom when a beat drops with the Relentless. For me, I don’t have anything bad to say. You either like it or you don’t. I grew up on bass and so the last thing I am is allergic to it. No sir, give me quick but solid, deep yet agile, give me robust yet defined and I’ll be a happy camper.

What an absolutely sharp looking set!


The Celest Relentless has a nice sounding midrange for a V-shaped set. Typically, V-shaped iems aren’t well known for their fantastic mids. I certainly wouldn’t label the midrange as the Relentless’ strong suit. However, it isn’t a weak point either. You’ll notice there is a good mix of crisp and smooth without one aspect of the sound dominating another. At least that I’ve heard. I don’t hear a ton of BA metallic timbre, which is huge considering the Relentless is set at $169 and has a DD and two BA’s controlling them. Also, I hear good cohesion of the drivers which is another nice aspect of the tuning. Note weight is on the lean-lush side. Not heavy and weighted, but not thin and dry either. There’s some tackiness there. Not perfectly natural but also, I don’t hear anything that’s clearly unnatural either. I do hear a very slight recession (if you want to call it that) in the lower midrange, however this does nothing to take away from the clarity and presence in this region. The Relentless doesn’t have many weak points and I certainly don’t consider the midrange one of them.

Good for technical stuff…

Transparency is one of the Relentless’ “pros” (if you want to call it that) while at the same time keeping very tight transients. This bodes very well for the technical stuff in this region. Details within the midrange are obvious and instruments seem to be well partitioned off and separated pretty well with nice fine-lines which conto midrange note edges and also come through much better due to the mostly black background. I don’t hear any crazy masking, blurring, or veil either. To be honest, the only thing that I do hear from time to time is some slight sibilance on the right tracks. This may be a bother to some, but not bothersome to me as it isn’t too obnoxious or exaggerated.


Like I pointed out, the low-mids do have the slightest recession from the rest of the mix, sounding a hint further back. Actually, scratch that. They don’t sound further back; they just don’t sound as forward. If that makes any sense. Having said that, the low-mids are very clean. This area has some good “presence” in the face of this subtle recession. To me the bass doesn’t really creep into the midrange in a detrimental way. The very slight bleed does provide some warmth to lower midrange vocals and instruments, but it isn’t going to make them overtly warm or weighted. There’re good air gaps between instruments and voices, and I don’t hear any real recessed blurring if the sound field here. Males sound perfectly fine. Perhaps there are some sets which put them more on a pedestal, but the Relentless sound good. Males like Chris Cornell in the track “Nothing Compares 2 U” sound slightly less energetic than other sets but also very clean. His voice doesn’t sound too edgy as it usually does. I feel he comes across nicely actually. Recession or not. Also, a voice like Cody Johnson‘s in the track “The Painter” comes across with good and solid note weight. His voice has an authoritative infection that sits just ahead of the instruments. I do like that I can hear nice separation of voices and instruments as well.


The upper-mids have more shimmer to them. They are forward and well composed. I don’t hear anything that I would consider to be too glaring or shouty either. The upper mids have just the right amount of sparkle in contrast to the bass. Females sound well accentuated but not overbearing. A voice like Kacey Musgraves in the song “Deeper Well” has almost a euphonic quality to it. Her tone and timbre are so very tuneful with good energy at attack. She has that high register softness that still has somebody to it which the Relentless is able to show off. Coincidentally, I like it a lot. Or a track like “Buffalo” by Hurray For The Riff Raff. This is another track which really draws the female voice forward, front and center, and she sounds very melodious. The musicality in this region is nice. No females or instruments sound dry or papery while at the same time there’s still that bodied crispness to their voices. Don’t get me wrong, I’ve certainly heard better female vocals. Despite that, females sound propped up, foregrounded, emphasized and actually decently bold too. For a V-shaped iem the upper-mids aren’t too bright or piercing and they actually are more composed and controlled than anything else. I wouldn’t say that the upper-mids are the most natural sounding that I’ve ever heard. They are a hint too elated sounding to be considered organic or natural. That said, they sound clean, detailed, transparent, and very well composed.

Downsides to the Midrange

The first issue that some may find in the Relentless’ midrange may be in the lower mids. I don’t have a problem with the slight recession in this region but I’m just me. I’m sure some would like an even more forward and more weighted low-mid. Another slight issue to my ears is the sibilance which does show up in the upper mids every now and again. I honestly don’t even pay attention to it… Until I do and then I cannot unheard it. However, it isn’t so blatant that it’s annoying to me. Also, there is the slightest tinges of metallic timbre from time to time. I’m telling you; it’s not going to upset many. It’s very slight. I simply felt that I needed to get that across.

I know that some folks are going to have issue with the midrange, it’s just how this hobby works. But I don’t think that there’s many hybrids that are outright better in this region apart from something tuned to accentuate this region like the Letshuoer X-Gizaudio Galileo. Of course, that set has other issues. Again, this is a bass forward, upper-mid/treble forward iem. This should render the meat of the midrange pushed back and slightly more mixed in with the rest of the mix. Not as highlighted. However, I don’t hear that all the time. I suppose the clarity and airiness of the sound with good denseness of note body does help to accentuate certain aspects of the sound. That and the fairly clean background.


Treble Region

The treble region is certainly emphasized and pretty bright at times and on the right song. Not to a fault though. I want to make that clear. Maybe to some, but not to this guy who’s spent too many hours to count with the Relentless in my ears and rarely did I feel I was hearing outright shrillness. Again, well controlled, very well detailed, well separated, good treble bite as well. The Relentless offers treble notes that have a snap to them which gives added life to the sound. Notes have roundness to them all the while the Relentless has some crispness too. I’d still say it’s smoother overall, however. Maybe not the crunch of a good EST driver, but good for customized BAs at the price. Extension into the upper treble is one of the Relentless’ strong suits providing a feeling of levity, of air, and a wider stage.

Speed and contour

Listening to Billy Strings in the track “Ice Bridges” the Relentless easily handles this fast-moving track. Billy’s banjo works at very fast speeds and with the Relentless I can hear each separate attack and the release or conclusion of each note relatively well. I feel there are many contributing factors into how well the Relentless is able to provide delineated and complete notes which don’t sound blurred or tizzed out in treble sheen. For one, it has that air I just talked about. This brings on a sense of space and separation. Add to that, the imaging is very nice. I don’t hear instruments floating around the sound field. They are reasonably stationary. So, couple that with space, cleanliness, transient swiftness and good note definition and you have yourself a pretty nice treble region. The Relentless does have a speedier treble but yet doesn’t always lose its contoured and glass lined edges. It isn’t grainy or fuzzy. Unless you are listening to some electric guitar blare session, but also… Most sets won’t come across very cleanly separated and contoured on those tracks.

It can get bright

I do have to emphasize that the treble can become pretty bright. I feel that this is warranted due to the lift in the bass which forms (in my opinion) a very good dynamic balance between the two regions. Still, it’s bright and some tracks will exaggerate this more than others. Having said that, I don’t feel I’ve had even a moment of wincing or wanting to lower the volume. Yes, it’s bright but it isn’t shrill. There’s a difference. Celest did a fine job tuning a more fun and macro-dynamic expressive sound that is also very tame and contoured. The treble is no different. I don’t hear something that I would consider artificial resolution either. Celest did a balancing act and it’s tastefully done. In fact, timbre up top is just off-natural. Close, but a tad more energy than realistic. However, the treble region definitely doesn’t sound bad in my opinion. Also, who’s to say what “natural” sounds like. Instruments all have a nice enough timbre as the Relentless doesn’t have abrupt spikes and the sound is pretty cohesive up top. I think at the end of the day the Relentless has a very nicely tuned lift which extends pretty darn far into the upper treble offering very nice details and a more open feeling stage.

Downsides to the Treble Region

Of course, the main issue that some will have in this region is the emphasis up top. It will come across to some listeners as “too bright”. Those who enjoy a warmer or darker treble region will probably not appreciate the amount of treble energy. Plus, the Relentless can at times tilt the scales of “too bright”. It’s rarely the case but should be mentioned. I feel that treble heads may enjoy the lift here as well as the quality of treble but certainly there are a multitude of hobbyists who are very sensitive to a bit more treble energy.




The stage is a bright spot in this set. Like I said a few times already, there is a sense of air and openness with good extension both ways. Both in the sub-bass as well as the upper treble. Without question the stage is above average in width, in my opinion and against what I’ve heard within the price point. I also find that the height is better than average too. Now, depth is there but I don’t feel the Relentless is some holographic sounding 3D style listen. There is depth for layering, and it is noticeable enough. This isn’t some grand coliseum or some enormous stadium, but it is airy, and the stage dies feel decently vast for an iem. Of course, we do have to remember that the Relentless is in fact an in-ear monitor. You can only get so big folks. However, it’s nice.

Separation / Imaging

When listening with the Relentless in my ears I can unquestionably hear good separation of elements within an imaginary stage. I keep repeating myself, but the sound is open, clean-lined, and depending on the track the Relentless can have very good separation. There are some very bass heavy tracks which will blurry the sound field a bit more but also, who’s seeking perfect separation in a bass dominated track? Like I said earlier, in some blaring and complicated heavy metal tracks you’ll get some congestion that the Relentless cannot do very well against either. But again, how many sets can? 98% of my listening, the Relentless proved its salt folks. It can partition off elements of the stage very well with quick drivers, tight transients, and great resolution. The same can be said of its ability to image. Left to right and front to back are pretty easily discernable. Imaging is solid.

Detail Retrieval

There are some iems which specialize in detail retrieval, and they will have the upper hand here by doing what it takes to get those mind-boggling good details. In the same breath, those sets mostly miss out on some other aspects of listening. With this thought in mind, the Relentless is able to illuminate the minutiae within my music very nicely and still remain fun and musical. Whether it’s the breath in a mic from your favorite female singer, the screaming fan in a live track, finger slides on a guitar, different harmonics which seem to come through easier etc… The Relentless will bring out those details pretty darn well. I certainly wouldn’t call its ability to retrieve details as one of the Relentless’ “specialties”, but I would absolutely call detail retrieval a “pro”. Of course, just like in separation and imaging, there are some tracks that simply won’t be as transparent, and details will likely not come through as well. This should be expected. However, in the grand scheme of things the Relentless performs admirably.

Celest Relentless / QOA Aviation


QOA Aviation ($199)


The Queen of Audio Aviation (Aviation Review) is one of those sets which entered into the game quietly, but folks got pretty loud about it fairly quickly. I decided to keep it in the family with this comparison. If you don’t know, QOA is a sister brand of Kinera. Anyways, no doubt this is a stellar iem coming in at $30 more than the Relentless ($199/$169). The Aviation is a four-driver hybrid consisting of one 8mm dynamic driver as well as three Knowles balanced armature drivers. Folks, I really enjoy this set. From top to bottom and front to back the Aviation is a special set at $199. So why would I subject the Relentless to a comparison? Well, I simply think the Relentless is that good. Yet even more-so, I feel that anyone looking in the price range of the Relentless may naturally want to see what’s in the next price tier. If a hybrid is what they are after, then the Aviation is a logical set to take a look at. Does it make sense to save a hair more and go with the Aviation? Well, I will try to answer that from my perspective. Of course, these two aren’t very alike tuning wise if you are looking at the graphs. However, they really don’t sound all too different. This should be a good comparison for me.


To start, the driver count is obviously a bit different (7 to 4), the drivers used are a bit different, and the overall tuning is a bit different. Also like I said, the price marks a $30 difference. I can tell you that the Relentless are quite a bit larger in size. Obviously due to having more drivers the size is appropriately bigger. Both have beautiful all-resin builds. Also, both iems have absolutely gorgeous faceplates areas. I do like the look of the Relentless a bit more but that’s just my opinion and taste at the moment. Both sets come with great unboxings. I’d say they cancel each other out, both are phenomenal for the price. Kinera knows how to make a 1st Impression. I do like the cable on the Relentless more and the carrying case of the Aviation. They trade blows. The Relentless is a couple volume steps harder to bring to volume, but both sets are rather easy to drive. There are certainly some differences between the two. Let’s look at the sound.

Sound Differences

Now, if you look at the graph, you’d think that these two are worlds apart. This isn’t completely the case from casual listening. However, there are certainly differences as you listen more closely. Now both iems are slightly warmer in tonal coloration, both sets favor musicality first, low end quantity is about the same on both. That said, the quality of the Relentless bass is better. It’s tighter, it’s more impactful too and able to take on complicated tracks a hair better. Remember, these are very small differences folks. The mids on both sets are on the warmer side but the Aviation has a meatier note weight, lusher vocals too, but also not nearly as clean as Relentless is. The Aviation is more organic for sure, more natural sounding too. One subtle difference is that the Relentless does have that teensy bit of BA timbre on tracks with a lot of upper-mid energy, whereas the Aviation doesn’t at all. Yet the details coming from the Relentless are much better than the Aviation. Resolution is better, transients move with better tightness and agility on the Relentless too. I would say the Aviation is more emotional of a listen and more musical as well. The treble region of the Relentless is brighter, more detailed, better extended, has more treble bite and punch, crisper, yet also you could say it has a better shot at piercing brightness too. That’s something to measure and weigh. The Aviation is simply easier on the ears, more relaxed too.


I can tell you straight up that the Relentless wins out in almost all technical categories. Please don’t take this as though I’m saying the Aviation is devoid of these attributes either. I am not saying that. If Aviation is average at details, then the Relentless is above average. Average is good though. Anything “less than average” is not good. Aviation does fine and excels at other areas which make it an awesome set. However, I digress, the Relentless does have more pep and energy in its sound with more energy in the treble which translates to better perceived resolution across the mix. It has better detail retrieval; separation and the stage feel more open sounding. Imaging is actually good on both sets.

Further thoughts on this comparison

To finish with this comparison, I would first ask you to simply pick your poison here. Both are very well tuned and likely would be adored by different segments of the community. So, I do have to call this a preference battle. As alike as they can casually sound, they are actually quite different in quite a few ways too. Personally, I’m on a honeymoon with the Relentless, but I do really enjoy the QOA Aviation. It really honestly is a fantastic iem. Is the $30 more worth it… probably not if you prefer the Relentless’ signature. However, if you dig that earthy, lush and organic sound with a musical flare than the Aviation is a great set at its price point. Yet if you want something cleaner, tidier, faster, more resolute with a fun signature and great extension both ways than the Relentless is likely more up your alley.

Graph courtesy of Tone Deaf Monk, Thanks!


Is it worth the asking price?

Okay, now we get to the real question. Is the Celest Relentless worth the $169 that Celest is asking for? I suppose this depends on what you prefer and your budget. For me it’s easy… absolutely it is. It’s a very fine iem. That all said, for the consumer you’d have to measure and weigh all of the other hybrids at or around the price point to really get a great idea how you’d answer this. I understand too, there’s a lot of fine iems around this price. Are there a lot of good “hybrid” iems in this range? Yeah, there is. Are they as good as the Relentless? Maybe. The CCA Hydro (Hydro Review) is about $50 cheaper and is a fantastic iem. Do not sleep on that set. The Celest Phoenixcall (Phoenixcall Review) is another awesome Celest brand hybrid iem. The Pula PA02 has gotten a lot of love. Sound Rhyme SR5 is another nice set. Kinera Idun Golden (Mahir’s Idun Golden Review) is under $200 now. The Hidizs MS3 (MS3 Review) is really a nicely tuned iem. Also, the Binary X-Gizaudio Chopin (Mahir’s Chopin Review) is a special set from many hobbyists. Truthear Nova (Sean G’s Nova Review) is a set that’s gotten a lot of attention. Also, one of my personal favorites which just dropped under $200 is the Rose Technics QT9 Mk3 (QT9 MK3 Review). I could keep going for quite some time friends. Basically, there’s a lot more to name and a lot of competition.

The Why?

Because the Relentless is built very well with a HeyGears 3d printed build. The design is second to none in the price point. It is exceedingly slick and totally gorgeous. This pair is very light on the ear and feels like nothing over long listening sessions. Still, like all iems or audio devices the real worth will always stop and start at the sound. Good for the Relentless because this happens to be its greatest strength. This set sounds very good for $169 folks. That deep yet tight bass which can handle most anything you throw at it. It’s full and fun and nicely dense. The mids compliment the tuning well with loads of details and very nice resolution. Another good subjective reason why is that the treble has that bright yet not overly fatiguing sound which also has awesome details and also has great resolution. The treble is energetic, punchy, and has some very good extension into the upper treble. Technically the Relentless does a great job, nice stage, separation of elements of that stage and great imaging within the stage too. Really a fine set and yes, 100% the Relentless is worth the asking price. This one is a rec for sure.


Ratings (0-10)

Note: all ratings are based upon my subjective judgment. These ratings are garnered against either similarly priced sets or with similar driver implementations or styles with the unique parameters of my choosing. In the case of the Celest Relentless ratings below, that would be $100 to $199 hybrid driver earphones. Please remember that “ratings” don’t tell the whole story. This leaves out nuance and a number of other qualities which make an iem what it is. A “5-6” is roughly average and please take into consideration the “lot” of iems these ratings are gathered against. $100 to $199 is a large sized scope of iems and it is very competitive. It’s a large enough pool of iems that seeing a “9.0” for example, should mean something. My ratings are never the same and each set of ratings tells a different story. Each time you read one of my ratings will be unique to that review. Basically, I create a Rating that makes sense to me.


Build Quality: 9.1 Built well, HeyGears build.

Look: 9.9 Tops in class.

Fit/Comfort: 9.5 Fit and comfort is great for me.

Accessories: 9.6 Accessories are very nice.

Overall: 9.5🔥🔥

Sound Rating

Timbre: 8.9 Great timbre for a hybrid.

Bass: 9.6 Deep, robust, impactful, tight.

Midrange: 9.1 Resolving, detailed, dynamic.

Treble: 9.4 Extended, detailed, precise.

Technicalities: 9.3 All technicalities are great.

Musicality: 8.9 Nice musicality

Overall: 9.2🔥🔥🔥

Ratings Summary:

Looking at the ratings above, I pitted the Relentless against any hybrid iems between the prices of $100 to $199 US. Of course, do keep in mind that I can only do so against sets that I’ve actually heard and know very well. If I’ve just heard a set a time or two, I don’t consider that something I should be judging the Relentless (or any set for that matter) against. The bonus is that I’ve heard a lot of them and feel I have a pretty good grasp on how I feel the ratings should go. I do ratings because I have to, but I don’t agree with them all too much. Too vague for something which takes a ton of nuance and explanation. Also, we are all so very different and on top of that, the personal audio market changes by the day which does a lot to render ratings almost useless after about 6 months to a year. At any rate, here we are.

Explain Yourself!

I don’t feel there’s anything that is too controversial here. I could see folks who like an even more robust and bulbous bass thinking that I’ve rated the Relentless too high in the “bass” rating. Musicality is a made-up interpretation that we like to use and throw around like there’s some hobby-wide understanding of what “musical” is. I’m here to tell you that that is a ridiculous thing to say. Musicality is a subjective opinion based on… Something. My subjective opinion is that the Relentless is a “8.9” against my prescribed field of hybrid iems. Without question there will be those who don’t agree. I expect that. To be honest, I could see someone arguing over any of these ratings. Of course, they’d be arguing to a wall because I’d never argue something so personal to each person. I simply say… “okay”. Everyone is always right all the time in this hobby… Every day of the week. That’s about it, this set is great, and it deserves such a high overall sound score of a “9.2”.



To conclude my full written review of the Celest Relentless I want to thank Kinera, Celest, and mostly I’d like to thank HiFiGo for putting this sample together. You can get the Relentless HERE at HiFiGo as well as a few other locations I have linked at the beginning of the review. Guys and gals, I go into each review with two goals in mind, and that’s to help you in your quest to find something which can bring you joy. And two, I need that creative outlet to explain my thoughts exactly how I see them concerning whatever product I’m featuring. For me it’s a joy to do.

Thanks, HiFiGo!

I cannot thank HiFiGo enough for never getting in my way. They’ve never once even whispered to change my words, pre-read any review, they’ve never even asked me to skew a review in any certain way. Never offered to pay for a review. Never. Please trust me that this isn’t the case with every brand. Hence why I don’t review with certain stores and certain brands (which we won’t talk about). I cannot have my integrity sold out so that a store can make a few extra bucks. HiFiGo has never asked me to publish anything other than my authentic words. Again, never even a whisper. If I don’t like a product, I won’t review it. Plain and simple, of course there are always caveats to this rule. Yet generally the rule applies. Either I like it, or I feel that a good segment of hobbyists will enjoy it. I’m not wasting my precious time on something I or anyone else won’t enjoy (Unless it’s a tour product, that’s different). At any rate, Kinera has been nothing but a blessing for my review life and they’ve always been wonderful to work with. Very kind people. So, thank you!

And thank you!

Also, thank you to you, the reader, the consumer, the person trying to figure out where your money is going to best serve your joy. Thank you for reading this. Thank you for clicking the link. Each time you do it is a help for our website. Each click tells the algorithm that we should be closer to the top of the search index and the longer you stay the better. We are a small group of passionate audio fans that truly enjoy reviewing and featuring. So, thank you.

Different Perspectives

For your benefit, definitely check out other thoughts on the Relentless. Don’t rely on me and then go and hit the “buy now” button. We are too far different, and this hobby is completely subjective where personal taste and personal opinion rule the reviewing world. Don’t be fooled to think that any one reviewer is some golden standard with golden ears. This is a hobby, and we are humans. The hobby is very diverse and so are we. So, it will likely be worth your while to listen, watch, or read other reviews. With all that said, I think I’m done. Folks, take very good care of yourself and those around you, stay as safe as you can and always… God Bless!

Great review, would you see it as a major improvement over the Pheonixcall?
What a comprehensive review this is
Great review and Front page! Well deserved.


New Head-Fier
Kinera Celest Relentless: Ambiguity
Pros: Lovely design
Solid package
Interchangeable plugs
Punchy bass
Wide and deep soundstage
Cons: Large shells can be uncomfortable for thin ear canals and small ears
Dependence on the source
Muddy and swampy mids
Unlined treble
Review of Kinera Celest Relentless


Greetings to all audiophiles, audio enthusiasts, and those who are just starting their journey in this wonderful hobby. Today, I'll be talking about a new release from Celest - hybrid IEM Celest Relentless. Honestly, I really appreciate Celest's attention to detail in both sound presentation and accessories. Previously, I reviewed the Celest Pandamon 2.0 and enjoyed their airy sound.

So, let's talk about the new release. On March 18th, Celest, a sub-brand of Kinera, introduced their new product - the Celest Relentless. Celest’s drew inspiration from ancient Chinese mythology, specifically the "Shanhaijing" ("Classic of Mountains and Seas"), where, according to legend, a young girl named Lass tragically drowned while swimming in the East China Sea. Later, she transformed into a bird named Relentless and took on the responsibility of protecting other creatures by reclaiming sea. Design and tuning of Celest Relentless are based on this tragic and heroic story of a young girl, Lass.

I wish other companies would also pay attention to the history of their product during their creation and follow Celest's example.

Well, as far as i understand, these IEM have replaced the PhoenixCall with a more advanced driver configuration. In this version, they abandoned two micro-planar drivers intended for ultra-high frequencies in favor of an additional 4 balanced armature drivers. So, Relentless is equipped with one 8mm dynamic driver and 4+2 balanced armature drivers.

Celest claims that the sound signature of this pair is highly balanced with deep bass, clear vocals, and detailed treble. Whether this is true, we will find out in this review, and I'll do my best to make it as useful as possible for you.

I would like to thank Alice from the HIFIGO store for providing the opportunity to test and review this product.
Disclaimer: My review is my personal, honest opinion about the product. I don't receive any income for conducting reviews and i'm don't participate in any affiliate programs.
You can purchase the Kinera Celest Relentless from:

  • 1DD+6BA Hybrid Driver Configuration;
  • Impedance: 27Ω;
  • Sensitivity: 105dB;
  • Frequency response range: 20Hz-20kHz;
  • Connector: 0.78mm 2-pin;
  • Cable material: 5N Copper Silver-Plated Cable;
  • Price: 169$.

What's in the box:
  • IEM itself;
  • 2 pin 0.78mm 8 core cable with 5N Silver-Plated Copper braid, 1.2m length;
  • 3 sets, 8 pairs Celest eartips: 3 pair - Celest 221 gray vocal eartips (S / M / L), 3 pair - Celest 608 black & red balanced eartips (S / M / L), 2 pair - Celest foam eartips (S / M);
  • Interchangeable plugs: 3.5 mm, 4.4 mm;
  • Cleaning brush;
  • Golden bird souvenir;
  • Carrying case.

First impression, Design, Comfort, Additional accessories

First impression

My acquaintance with the Celest Relentless started with the package. Package itself is designed in blue tones with an image of a bird on the front. It also indicates that this is a single-dynamic with six balanced armature drivers.
The back of the package tells the story of the Relentless and provides their specifications. When i opened the package, my first impression of IEMs was that they were made for big humans. Shells are large due to the seven drivers inside them. A thick cable with an 8-core braided and a 4.4 mm balanced connector was inside a protective case marked "Celest." Also inside the case were three sets of ear tips and a 3.5mm plug.



Relentless are made of resin using 3D printing. They are slightly transparent, allowing you to see the drivers installed inside. Weight of each 6 grams. The faceplates features a sea foam pattern resembling a bird's wing and the calligraphic inscription "Celest". It looks like genuine art.
There is a one compensation hole next to the 2-pin connector.
The nozzle is positioned at the right angle, wide enough but not too long, which may cause issues with selecting eartips for comfortable fit and sound isolation. I want to warn you that thin ear canals may experience discomfort due to wide nozzle.
There is an edge at the end of the nozzle for securing the eartips, and a metal mesh inside.
During the time that I have been using the IEMs, I have not had any issues with the build quality. All the parts are carefully made and I have not had any complaints about the build.



Celest has ensured a comfortable fit in the ear by making the Relentless shells ergonomic. Thanks to correct angle of nozzle and convex inner part of the shell, fit in ear doesn't cause any discomfort, even for a small ear.
However, after an hour session, a slight pain occurs in ear canals, which is annoying and makes me stop using. Overall, i can't recommend this set if you have a small ear and/or a narrow ear canal.
These are largest shells among all IEMs in my collection. Sound isolation is excellent. I assure you, once you put them on, you feel completely isolated from external sounds.


Separately i would like to mention stock cable. It's a good-quality cable, long, flexible, and sufficiently thick. It features an 8-strand braid made of silver-plated 5N copper. Outer shell is made of soft PVC material, ensuring protection against damage and water resistance.
One end of the cable has a detachable connector for connecting either a 3.5mm stereo or a 4.4mm balanced plug (by default, it's set to 4.4mm).
On the other end are aggressively shaped ear hooks, and at their ends is a 2-pin 0.78mm plug.
Overall, this cable reminds me of the TRI Through cable, but with the 'Celest' branding."

Ear tips

Before discussing the sound of these IEMs, i want to mention about included sets of eartips.
First ones i tried were Celest 608 balanced eartips, red with black. Sound reproduction with these tips felt incomplete to me: there was a lack of treble and lows, and midrange sounded muddy and swampy, as if the lows and treble were cut off.
With the Celest 221 wide bore gray eartips, set sounded fuller, richer, and more balanced, which i liked more.
However, after trying several eartips, i stopped on TRI Clarion, which fully revealed IEM's tonality.



In terms of driveability, this set behaves very strangely. Let me tell you why.
First thing i did was connect the IEMs to my main device - Qudelix 5K. and i realized that they sounded muffled and tight. Connecting them to the phone via Bluetooth with the Qudelix 5K didn't change anything. After that, i experimented a lot with various sources for these IEMs. I tried connecting them directly to PC, laptop but got same effect. Connecting to an iPad Mini via the Apple dongle made it slightly better; the sound opened up and became more liberated.
In the end, I found an old Xiaomi phone, and oh wonder! IEMs breathed new life. They gained a spacious sound, and Relentless seemed to breathe again.
Eventually, i came to conclusion that the simpler source used, the better Relentless would perform.
P.S. I didn't have the opportunity to test with a balanced connector due to the lack of a source with a balanced output.

Sound Impression

First thing i noticed when plugged in the Relentless was that they sounded spacious but muffled. After trying out several sources, i managed to achieve satisfactory sound quality.


(I tested IEM with TRI Clarion and Tangzu Wide Bore tips, connected via 3.5mm)


Let's start with the bass. Extended and deep.
The bass is handled by an 8 mm dynamic driver which tends to reproduce lows.
Let's begin with the sub-bass. It's well perceived with its fullness and is achieved through a meaty rumble. Sub-bass here is deep but quite fast. It feels like an aerosol spray. Overall, i wouldn't say it adds any richness to the bass – mixed feelings.
Mid-bass. More interesting here
This is where the Celest excels. Body of bass is deep, rumbling, and energetic. Hits are accurate, with a prolonged attack. Bass guitar plays with drive and energy, and drums have a sustained attack. Mid-bass, due to its duration, decays slowly and smoothly.
As an example of bass guitar and drum sound, i can mention "Double Image" by Miles Davis.
Bass is not overpowered in these IEMs, so I cannot recommend them to bass lovers.


Mids. If i had to describe them in a few words - on the brink of failure.
Midrange is handled by a pair of custom Celest 29689 balanced armature drivers. If you appreciate midrange with a BA flavor - you are welcome. For me, mids sound tight and constrained, but at the same time airy and disheveled. But let me try to explain step by step.
Lower mids have a deep sound, but i wouldn't call it musical. Guitar sounds unnatural and gets lost in the overall mix of the song, it feels constrained. Overall, if you focus solely on the guitar, its sound doesn't seem that bad. Saxophones and clarinets in jazz sections have a rich and saturated timbre.
Midrange segment. Flat hole (barrel).
This is where all the problems start. Let's start with instruments. Like we have a delicate violin, guitar strings lacking some fullness, piano keys playing full-sized, but vocals...
Vocals here are produced within the composition, neither behind nor in front. Timbre of the vocals lacks detail, very tight and constrained. I didn't feel any energy in either male or female vocals. It feels like the vocals are placed in a big bag.
Upper mids. Harmony and friendship.
For this segment, I connected the Relentless to a different, brighter source, and what can I say? Timbre of female vocals leveled out a bit, becoming more harmonious against the overall composition, timbre of instruments became more expressive but didn't lose its BA flavor.

Treble. Quantity doesn't mean quality.
The treble are handled by four small custom balanced armature drivers, model Celest 10012. I believe this is the same driver as in the predecessor - Phoenixcall.
Treble here sound bright, clear, with a slight metallic flavor. Let's start with the low highs and treble. This range remains understated, unremarkable, and cut off. On the other side, treble are airy but quickly decays. Sibilance aren't annoying.

Separating, sound stage:

Soundstage. That's what creates the "wow" effect.
If you close your eyes, you can visualize yourself inside the instrumental sound. Each instrument is positioned at a certain distance and height from you. Soundstage here is wide and deep, but with one drawback — it's not tall enough.
Separation here is excellent. Each instrument is positioned at a distance and doesn't interfere with each other.


Kinera Celest Relentless vs Simgot EA500LM:

My first comparison i want to make is with Simgot EA500LM.

Let's start with design. Relentless is larger and made of resin, while the Simgot is made of metal. Simgot is more suitable for most people due to its streamlined shape, but sound isolation is better in the Relentless. Simgot is easier to drive.
In terms of sound, these are two completely different models. Simgot is single-dynamic driver IEM delivers very detailed, precise, and vocal sound, providing an analytical experience. Relentless, on other side, have good multifaceted sound with good separation and expansion.
Delving into the details, bass in Relentless is more punchy and deep. Mids in Simgot sound better, more saturated, they are more detailed and pushing forward. Detail retrieval is definitely better in the EA500LM. Treble of Simgot are brighter and more clearer, while Relentless's they are more airy.

vs Kinera Celest Pandamon 2.0:

Let's start with design. Pandamon 2.0 is smaller, lighter, and has a longer nozzle. Relentless is more comfortable in the ear due to its ergonomic shape. Sound isolation is better in Relentless. The Pandamon 2.0 is a bit easier to drive.
In terms of sound, Pandamon 2.0 is brighter and more dynamic, with the mids pushed to the forefront, while lows are deeper in Relentless. Relentless provides better separation and soundstage, offering a more expansive, 3D-tuned sound where each instrument has its own space, creating a mesmerizing effect.

vs Simgot EW200:

EW200 have a more compact shells, they are lighter, made of metal, and have a smaller nozzle. As a result, EW200 provides the most comfortable fit I've ever experienced. Relentless are better suited for medium/large ears due to their ergonomic shape and provide better sound isolation.
In terms of sound, EW200 are significantly brighter in treble, mids in EW200 seem more pronounced, whereas in Relentless they are less forward. In bass range, Relentless outperform thanks to their deep and punchy bass. Separation and soundstage in Relentless are significantly wider and deeper.

For whom are these earphones

I would recommend these IEMs to those who like to take risks, who enjoy energetic music. Those who enjoy experimenting, who like a large form-factor of shells.
For fans of Celest's sound signature, who are knowledgeable about sound creation.
For those who enjoy the armature sound of mid and high notes. Those who like a wide, layered presentation of the soundstage. Those who enjoy listening to expansive music.
Relentless is perfect for EDM, dance music, house, electro, and pairs well with old jazz, but is not suitable for orchestral and concert music.



I'm impressed with Celest's new release. They offer a unique, memorable sound that may not be suitable for all audiophiles, yet the sound is smooth, soft, neutral, and enjoyable. Yes, there are noticeable drawbacks, such as the unnatural mids under the influence of armature tuning, but overall, diving into the IEMs sound, you'll definitely enjoy it. And with the right source, you'll feel pure pleasure.
The lows here are dense, adding richness to the overall composition, while the highs are crisp and clear, without overshadowing overall sound. Combined with a huge soundstage where you can hear every instrument, it's simply magical.
Summarize, Relentless is a bold hybrid from Celest that's worth trying out to experience its airy, dynamic sound.

Thank you for reading my review!
Feel free to ask questions below, i will definitely reply



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Can you try Velvet & Final tips
Hi, @Argha
Thank you for the suggestion. I have tried different tips on these IEMs, but the ones with a wide nozzle fit best. Included tips also work pretty well.
As for your suggestion, unfortunately, i currently don't have Velvet or Final tips to try and provide my assessment.


Headphoneus Supremus
Pros: Princely accessory line-up, including modular cable for balanced and unbalanced sources
Beautiful shells
Comfortable despite larger shells
Technical powerhouse, expansive soundstage and nice micro-detailing in particular
Decent timbre despite packing multiple BAs
Well-extended treble with lots of air
Good mix of bass quantity and quality
Cons: Moderate driving requirements
Treble is bright and occasionally sibilant, may not be the best option for treble-sensitive folk
Slight recession in lower midrange

I would like to thank HIFIGO for providing this review unit.

The Celest Relentless can be gotten here: (no affiliate links).

Relentless 11.jpg


For folks that are interested in a little ancient Chinese mythology, the "Relentless" namesake used for this IEM is actually from a touching story of a legendary guardian bird:

This legend hails from the ancient Chinese tome of the Classic of Mountains and Seas:

In bygone times, a girl named Nüwa drowned while swimming in the East China sea. Thereafter, she was reborn into a spirit guardian bird called Jingwei.

This diety bird swore to not let her tragic fate befall anyone else, and everyday, she picked up twigs and rocks in her beak from a nearby mountain, in an attempt to deposit these into the sea. The bird was determined to fill up the sea, one stone at a time!

Concluding the story, the sea mocked her, saying that she will never succeed in a million years. Jingwei replied stoically that she will spend ten million years - even a hundred million years - to accomplish her dying wish of not letting anyone else perish in the same manner. Thus came about the Chinese idiom of Jīngwèi tián hǎi (精衛填海) - which translates to relentless resolve even in the face of hopeless odds.

In fact, as we will read below, this IEM's shells and packaging feature a beautiful sea wave motif - in addition to a golden bookmark of the Jingwei bird - tying in nicely with this heart-rending folk story.

  • Driver configuration: 8 mm dynamic driver + 2 x 29689 balanced armature drivers + 4 x 10012 balanced armature drivers
  • Frequency response: 20 Hz - 20 kHz
  • Impedance: 27 Ω
  • Sensitivity: 105 dB
  • Cable: 2-pin, 0.78 mm; 5N copper silver-plated cable; modules for 3.5 mm and 4.4 mm terminals
  • Tested at: $169.99 USD


Other than the IEM, these are included:

- 3 pairs of Celest 221 "vocal" silicone eartips (S/M/L/)
- 3 pairs of Celest 608 "balanced" silicone eartips (S/M/L)
- 2 pairs of foam tips (M/L)
- Cable
- Modular plugs for 3.5 mm and 4.4 mm
- Metal bookmark
- Carrying case
- Cleaning brush

For a $100ish USD set, the accessories are very generous; essentially, everything that an audiophile would require is covered.

Relentless 10.jpg

The black Celest 221 tips are wide-bore and they boost treble and soundstage. The red Celest 608 are narrow-bore, and these increase bass, though with some stage compression. The foam tips provide the best isolation, albeit with a attenuation of the treble frequencies.

Relentless 9.jpg

The stock copper silver-plated cable is well-braided and tangle-free, with minimal microphonics. There's a chin cinch for added grip. It comes with options for 3.5 mm (single-ended) and 4.4 mm (balanced) modules, depending on your source preference. A nice touch is that the distal terminal has a screw on design, so that the module doesn't inadvertently drop out during usage, which is something not uncommon in flimsy modular cables which are just plug-on.

Relentless 6.jpg

The metal bookmark, as detailed above in this tragic story of the guardian deity bird, dovetails (no pun intended) beautifully with the Relentless moniker.

Relentless 8.jpg

Last but note least, we have a practical cleaning brush and a square leatherette semi-rigid case. The case is tough externally, with webbing and a soft material internally to cushion the contents.

The rest of this review was done with the stock cable and stock narrow-bore Celest 608 silicone tips. No aftermarket accessories were used, so as not to add any confounders to the sound.


Relentless 5.jpg

The housings are fashioned from HeyGears 3D-printed dermatologically-friendly resin. The faceplates are individually hand-painted, so each earpiece is unique! These faceplates showcase feathers of the guardian bird, coupled with waves of the tumultuous East China Sea, as per this storied narrative.

Relentless 4.jpg

The shells are semi-transparent, allowing consumers to visualize the acoustic tubing and drivers!

While on the larger side to accommodate 7 drivers per shell, the housings are light, and I had no issues using the Relentless for longer listening sessions. The inner aspects are smooth with no awkward protrusions.

Relentless 3.jpg

I did not encounter any driver flex on my pair. Isolation is slightly above average, and this IEM can be used in noisy places without much penalties.


The Relentless is a 7 driver setup, comprised of the following configuration:
  • 1x 8 mm dynamic driver takes care of the bass and midrange.
  • 2 x 29689 BAs settle the lower treble
  • 4 x 10012 BAs handle the upper treble


I tested the Relentless with the following sources:
- Apple dongle
- Cayin RU7
- Chord Mojo 2
- Fiio KA11 dongle
- Fiio KA17 dongle
- Khadas Tone Board -> Schiit Asgard 3 amp
- Questyle M15 DAC/AMP dongle
- Sony Walkman NW A-55 DAP (Walkman One WM1Z Plus v2 Mod)
- Sony Walkman NW A-55 DAP (Walkman One Neutral Mod)
- Sony Walkman NW WM1A DAP (Walkman One WM1Z Plus v2 Mod)
- Smartphone

This IEM has moderate drivability requirements. It is not an extremely easy IEM to drive, and will scale slightly with amplification, in terms of headroom and dynamics.


Celest Relentless.jpg

Graph of the Celest Relentless via IEC711 coupler.

Tonally, the Relentless sports a bright V-shaped tuning. It promises an exciting listening session, melding a big fun bass with a well-extended and resolving treble. This is in contrast to Celest's usual darker house sound.

This is a mid-bass focused set, with bass north of neutral, but just a bit shy of bona fide basshead levels. There's decent sub-bass rumble and an impactful mid-bass. The bass is surprisingly textured, with nimble speed and just a slight smattering of mid-bass bleed.

As per its V-shaped signature, the lower midrange is recessed to some extent, though thankfully there is no huge bass encroachment, so this frequency band remains relatively transparent. Upper mids hit about 8 dB ear gain, and vocals are forwards without pushing into overt shouty territory.

The Relentless has a bright treble, furnishing lots of resolution and clarity, with lots of air. This IEM will be a blessing for trebleheads for sure, though we do run into some instances of sibilance. Thankfully, for the treble-sensitive amongst us, this region can be tamed somewhat with the foam or narrow-bore silicone tips, in addition to perhaps using a warmer source or not playing the Relentless at high volumes (Fletcher Munson curve).

There's just a minor whiff of BA timbre, and for a set that packs so many BAs, timbral accuracy is surprisingly decent. Note weight is a tinge on the lighter side, but by and large, acoustic instruments and vocals sound quite natural (don't be expecting single DD levels of timbre of course).

Technical chops on the Relentless are quite something, with a huge soundstage, well-layered instrument separation and superb micro-detailing. The Relentless has one of the better soundstages for a $100ish IEM, with sound projecting quite far beyond the ears in width, with good depth and height to boot. Imaging is relatively accurate and transients are crisp.


The Relentless will be compared against other midFI hybrids. Single DDs, multi-BAs, and planars are left out as the different driver types have their pros and cons.

Binary X Gizaudio Chopin

The Chopin is a U-shaped set with a mammoth lower midrange/lower mids scoop out. Thus, the Chopin sounds much thinner and anemic in this area, with an artificial metallic timbre.

In technical aspects, the Chopin has a more claustrophobic soundstage, with weaker imaging and micro-detailing. The Chopin also has unique tear drop shaped shells which may possibly pose fitting issues.

Penon Fan 2

The Fan 2 is tuned warm neutral. It has a linear bass (with less quantity), though it has a thicker and lusher midrange than the Relentless. The Fan 2's treble is blunted, with some loss of resolution. The Fan 2 is however, more sedate and less sibilant in the treble. Of note, the Fan 2 is inferior in soundstage, micro-detailing and imaging.

Many consumers complain about fitting issues with the Fan 2's long nozzles, so this might be a potential deal-breaker.

Relentless 2.jpg


The Celest Relentless is one of the better $100ish hybrids one can get their paws on as of the time of writing. It compares very favourably against some similarly priced hybrid rivals, beating them in technicalities.

Segueing seamlessly into this poignant and stirring chronicle of the legendary guardian Relentless bird, this IEM has well-matched - and generous - accessories, elegant faceplates and comfortable ergonomics.

Bestowing a bright V-shaped signature, the Relentless has excellent technical chops, in particular micro-detailing and soundstage are the stars of the show. The bass has a good mix of quantity and quality, with a very resolving and extended treble making this the perfect set for trebleheads and detail-freaks. To top it off, timbre is surprisingly natural for something containing so many BAs.

It may be a tinge spicy for our treble-sensitive friends, but thankfully the treble region can be mitigated with foam tips or warmer source pairing or even playback at non-high levels (as per the Fletcher Munson curve). The midrange is a wee bit depressed - as per V-shaped style tuning - so mid-lovers might want to look for something else that beefs up the lower midrange more. However, it has to be said, the Relentless is not as anemic-sounding as something like the Binary Audio Chopin, which has a way more concave lower-midrange.

All things considered, the Relentless gets my recommendation for folks who are looking for a solid entry-level V-shaped midFI hybrid, which is beautiful on the inside and outside.
Last edited:
The shells indeed look beautiful but I find the bookmark tacky. Otherwise it's great to hear that there are affordable, technical V-shaped sets out there.


100+ Head-Fier
Celest Relentless Review: A Hybrid IEM with Exceptional Sound and Style
Pros: Powerful and well-controlled bass
Captivating midrange with natural presentation
Detailed and extended treble
Excellent detail retrieval capabilities
High-quality build and materials
Comfortable fit for long listening sessions
Premium cable with interchangeable 3.5mm and 4.4mm plugs
Exclusive looks with hand-painted ear shells
Great set of bundled accessories and ear tips
Cons: Ear shells are on the larger side
May not suit extremely treble-sensitive individuals with silicon ear tips

I recently had the opportunity to try out the Celest Relentless, a 7-driver hybrid in-ear monitor (IEM) known for its exceptional sound quality and craftsmanship. This IEM features a unique hybrid driver configuration, with an 8mm dynamic driver and 6 custom balanced armature (BA) driver units, promising a highly detailed sound quality tailored for audiophiles seeking an immersive listening experience.


If you're interested in purchasing it, you can do so through the following non-affiliate links.

Non-affiliate links:
  1. HiFiGo

Unboxing & Accessories

Starting with the unboxing experience and accessories, the Relentless arrives in an elegant blue box with a mythological story about a sea being called the Relentless printed on the back. Upon opening, you're greeted with the two earpieces and a small carrying case. The ear shells are particularly striking, with intricate designs like realistic sea waves. These shells are made by HeyGears, a renowned 3D printing design and manufacturing company known for their high-performance materials and precision design. The shells are crafted from a surface-treated resin, polished to offer a smooth look and feel. While the shells are on the larger side of average, their ergonomic shape ensures a comfortable fit.

The build quality of the Relentless is impressive, especially considering its price point. The ear shells are lightweight, weighing in at just 6 grams, which contributes to their comfort and fit. This attention to detail and quality craftsmanship enhances the overall user experience and reinforces the sense of premium quality associated with the Relentless.


Inside the case, the Celest Relentless comes with a variety of ear tips, including a set of narrow-bore silicon ear tips, a wide-bore set of ear tips, and two sizes of foam ear tips. The silicon ear tips are soft and comfortable, while the foam ear tips significantly alter the sound, as will be detailed in the graphs below.

Additionally, the package includes a golden-colored metal bookmark, which adds a touch of elegance. A well-crafted manual is also included for user guidance.

The provided cable is an 8-wire weave with average thickness, offering a soft and pliable feel. It's designed to resist tangling, a feature appreciated by many users. The cable features screw-in interchangeable terminations, with 3.5mm and 4.4mm options included in the box. The 4.4mm plug comes preinstalled, which simplifies the process of changing the cable termination without needing an adapter. The included cable cinch effectively secures the split wires in place, and two transparent ear hooks are there to help with fit and comfort. The cable terminates in 0.78mm 2-pin plugs, ensuring compatibility with the Relentless IEMs.


Design and Build Quality:

Celest's Relentless IEMs are renowned for their exclusive looks and meticulous construction. Each unit features hand-painted ear shells that add a touch of elegance and individuality, making every pair unique. The 3D printed ear cavities, crafted by HeyGears, ensure a comfortable and secure fit, ideal for long listening sessions.

The attention to detail in the design and build of the Relentless is impressive, reflecting Celest's commitment to delivering a premium product. The IEMs come with a 5N copper silver-plated cable that not only enhances sound quality but also adds durability. The cable is designed with interchangeable plugs,
which adds versatility and ensures compatibility with a wide range of audio sources without compromising on audio quality, allowing easy switching between 3.5mm and 4.4mm connectors to suit your audio source or preference.

Box Contents:

  • 1 x Celest Relentless IEM
  • 1 x Set of Celest 608 Balanced Narrow Bore Silicon Eartips (S, M, L)
  • 1 x Set of Celest 221 Vocal Wide Bore Silicon Eartips (S, M, L)
  • 1 x Set of Celest Foam Ear Tips (M, L)
  • 1 x Cleaning Brush
  • 1 x 8-Wire, 48 Strands of 0.006mm Silver Plated 5N Pure Copper Cable with 3.5mm/4.4mm Interchangeable Plugs
  • 1 x Manual
  • 1 x Metal Bookmark


Sensitivity: 105dB
Connector Type: 0.78mm 2-pin
Frequency Response Range: 20Hz - 20kHz
Cable Length: 1.2m
Plug: 4.4mm + 3.5mm
Cable Cores: 8 cores
Cable Strands: 48 strands of 0.006mm
Cable Diameter: 1.0mm/core

Fit & Comfort:

The Celest Relentless excels in providing a comfortable and secure fit, which is crucial for long listening sessions. The nozzle diameter is 6.4mm to 6.5mm, along with the earpieces themselves being on the average side, I found them to be extremely comfortable. The wide edge of the nozzle helps stabilize the ear tips, contributing to the overall comfort.

Thanks to the 3D-printed ear cavities, the Relentless offers a secure fit that ensures the IEMs stay in place even during extended use. This, combined with above-average passive noise isolation, allows for an immersive listening experience. I can happily say that I wore the Relentless for hours without discomfort, highlighting its comfort and suitability for extended listening periods.


Sound Quality:

The sound signature of the Relentless varies depending on the ear tips used—silicon or foam. With silicon ear tips (wide or narrow bore), the sound leans slightly towards a V-shape, emphasizing technicalities and details. On the other hand, with foam ear tips, the sound signature reduces the emphasis on treble while retaining a similar level of detail.

In terms of overall sound quality, the Relentless offers a satisfying and detailed sound signature across the frequency range. The 8mm dynamic driver unit delivers a solid bass response with good extension, while the Celest customized BA driver units enhance the clarity and resolution of the mids and highs.

The hybrid driver setup of the Relentless results in a pleasing tonality that impresses across the frequency range. The 8mm dynamic driver handles the lows with finesse, providing a rich, deep bass response that maintains control. The Celest custom balanced armature drivers excel in reproducing the mids and highs, offering clarity and detail that unveil nuances in music with exceptional precision.

graph (80).png


The Celest Relentless impresses with its bass response, offering good texture and depth. The 8mm dynamic driver unit delivers a deep, punchy bass that enriches the overall sound signature. Despite its emphasis on bass, it remains well-extended, providing a satisfying rumble in the sub-bass frequencies without bleeding into the midrange. This ensures a balanced and controlled presentation that doesn't overpower the rest of the music.

The bass of the Relentless stands out for its slam and impact, keeping up with fast-paced tracks and delivering a tight, impactful bass that adds dynamics to the music. Whether you're listening to bass-heavy genres like electronic or hip-hop, or more nuanced genres like jazz or classical, the Relentless handles the bass with finesse, providing a solid foundation for the rest of the sound spectrum.

As I said, one of the standout qualities of the bass on the Relentless is its slam, or impact. The dynamic driver unit of the Relentless is capable of delivering a punchy and impactful bass that adds a sense of energy and excitement to the music. Drums hit with a satisfying thump, while basslines have a sense of weight and presence that draws you into the rhythm of the music.

Overall, the bass performance of the Celest Relentless is nothing short of exceptional for this price bracket. With its powerful and well-controlled bass, tight and impactful sub-bass, and energetic slam, the Relentless offers a bass experience that is sure to satisfy many listeners with the exception of bass heads. Whether you're listening to electronic music, rock, or any other genre that relies on a strong bass foundation, the Relentless delivers a bass performance that is impressive.



The midrange of the Celest Relentless is another impressive aspect, offering clarity, detail, and a natural presentation that enhances the overall listening experience. This frequency range is where much of the musical magic happens, housing vocals and many instruments, and the Relentless excels in reproducing these frequencies with finesse.

One of the remarkable aspects of the midrange on the Relentless is its ability to handle both male and female vocals with finesse. The airy treble of the Relentless complements female vocals, adding sparkle and clarity that reveal the nuances in the singer's voice. Female vocalists like Adele sound particularly impressive on the Relentless, with a sense of presence and intimacy that captivates the listener.

In contrast, the bass of the Relentless adds weight to the lower midrange, enhancing the solidity and presence of instruments. This weightiness anchors the midrange, ensuring that male vocals sound natural and full-bodied. Male vocalists benefit from this added note weight, sounding rich and textured without being overshadowed by the bass.

Instruments in the midrange also benefit from the Relentless's tuning, with guitars, pianos, and other midrange-heavy instruments sounding detailed and lifelike. The clarity and separation of instruments in this frequency range are particularly impressive, allowing listeners to discern individual elements of the music with ease.
I noticed this aspect when I listened to some of my favorite orchestral music by Hans Zimmer. The bass added depth to the music, enhancing the weight of the notes, while the detailed sound of the Relentless helped keep the music distinct and separate.

Despite the Relentless's impressive bass and treble performance, the midrange remains coherent and integrated with the rest of the frequency spectrum. This integration creates a natural sound signature that is a pleasure to listen to, with each frequency range blending seamlessly into the next.


The treble performance of the Celest Relentless is a key aspect of its overall sound signature, offering detail, sparkle, and extension that enhance the listening experience across a wide range of genres. The treble on the Relentless is characterized by its clarity and energy, providing a sense of airiness and liveliness to the music.

One of the standout qualities of the treble on the Relentless is its detail retrieval. The IEM is capable of reproducing high-frequency nuances with precision, allowing listeners to hear subtle details in the music that might otherwise be missed. Instruments like cymbals, bells, and high-frequency strings are rendered with clarity and texture.

The extension of the treble on the Relentless is also noteworthy, reaching into the upper frequencies without sounding artificial. This extension adds a sense of airiness to the soundstage, creating a spacious and open presentation that enhances the overall listening experience.

Instruments in the high-frequency range also benefit from the Relentless's treble performance, with guitars, violins, and other high-frequency instruments sounding detailed and lifelike.

Overall, the treble performance of the Celest Relentless is outstanding, offering detail, clarity, and extension that enhance the listening experience across a wide range of genres.

Treble Variation with Silicon Ear Tips

The Celest Relentless has detailed and extended treble. However, with silicone ear tips, the treble may be too pronounced for those extremely sensitive to higher frequencies, especially with certain genres. Silicon tips can enhance treble, making it overly bright or harsh, particularly in classical or electronic music.

To address this, users can try different ear tip materials like foam, known for taming treble and providing a warmer sound. It's essential to experiment to find the best fit for individual ears and preferences.

Overall, while the Relentless excels in treble performance, extremely treble-sensitive listeners may need to adjust their ear tip choice to enjoy its sound quality fully.

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Technicalities, Imaging, and Soundstage

The Celest Relentless stands out for its exceptional technical performance, showcasing excellent detail retrieval capabilities that elevate the listening experience to new heights. With its hybrid driver configuration and expert tuning, the Relentless delivers a level of clarity and resolution that is truly impressive.

One of the standout qualities of the Relentless is its ability to reproduce intricate details in the music with precision. Instruments and vocals are rendered with a level of clarity and texture that brings out nuances in the recording, allowing listeners to hear subtleties in the music.

Additionally, the Relentless offers what I would call an average soundstage that provides a sense of space and separation between instruments. This spacious presentation enhances the overall listening experience, allowing listeners to feel immersed in the music.

Overall, the Celest Relentless is a standout performer when it comes to technical performance, offering excellent detail retrieval capabilities that will impress many listeners.


Truthear Nova

Comparing the Celest Relentless to the Truth ear Nova, the Nova's Harman Neutral tuning results in less bass, making vocals occasionally sound thin, especially male vocals. In contrast, the Relentless has better bass, enhancing instrument fullness and providing natural-sounding male vocals. The Relentless also offers superior detail retrieval and technicalities compared to the Nova. Overall, the Nova is suited for those preferring a Harman neutral sound with low mid-bass, while the Relentless caters to listeners seeking impactful bass and enhanced midrange.


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Moondrop Kato

Comparing the Celest Relentless to the Moondrop Kato, the Relentless offers a more pronounced bass and slightly better treble extension, giving it a more airy sound. The Kato, on the other hand, has a tighter and more controlled bass and a more neutral overall sound signature. Both are excellent IEMs, but the Relentless may appeal more to bass lovers and those looking for enhanced treble sparkle, while the Kato is better for listeners seeking a balanced and neutral sound.

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Moondrop Blesssing 2

Comparing the Celest Relentless to the Moondrop Blessing 2, both are excellent IEMs despite their different prices. The Relentless shares some tuning similarities with the Blessing 2, showcasing its skillful tuning. However, the Relentless offers more bass, upper treble extension, and airiness. In contrast, the Blessing 2 excels in detail retrieval, has less bass, and better imaging capabilities. Overall, the Relentless is ideal for those who prefer a bassier sound with extended treble, while the Blessing 2 is better suited for listeners prioritizing detail retrieval and imaging.

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In conclusion, the Celest Relentless is a remarkable IEM that excels in many aspects of its performance. From its powerful and well-controlled bass to its captivating midrange and detailed treble, the Relentless offers a sound signature that is sure to satisfy many listeners. Additionally, its technical performance and excellent detail retrieval capabilities further elevate the listening experience, allowing listeners to hear nuances in their music. With its hybrid driver configuration, expert tuning, and exceptional build quality, the Celest Relentless is a standout choice for anyone looking for a high-performance IEM that delivers on many fronts.
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500+ Head-Fier
“Different Done Right”
Pros: Cable has both a 3.5 and 4.4 option.
The packaging is beautiful worth the price.
Sound is lovely.
Upper trebble is perfect to my ears.
Works really well on instrumental tracks.
Insane value for the packaging and sound to my ears.
Cons: Mids could be too recessed for some.
Shell could be too large for some.
Air region could be too bright.

This is an interesting iem. It’s had a lot of retunes and the final graph isn’t something that I thought that I would like. I have the luxury of sometimes getting iems to test out without having read or heard a review. This is fun territory for me, and I can say that I’m a big fan of this unit.

This is a sample from Hifigo. Here are some non-aff links for you to check out if you’d like to buy it.

Amazon US:…
Amazon JP:

I’ve got the opportunity to review a lot of Kinera iems including the Dark Phoenix, Phoenixcall, and a few other iems. The have some unique tunings that are a little different from what I personally might buy based on my usual preferences, but this iem is one that I’m a huge fan of. Let’s talk why.

Let me share what music that I listen to:

Song Choice: Tidal list here:
I listen to a wide variety of music. I pick the songs because of various reasons. But I picture myself locked away like Andy Dufresne from Shawshank blasting music and shut off from the world. It’s a blissful image.
The Marriage of Figaro -The opera song from Shawshank Redemption, terrible recording but fun and gets me in the mood to listen to music.
O mio Babino caro -This is a modern less operatic version but a song with great female vocals.
Video Rigoletto - “La donna e mobile” Sung by one of the three Tenors, great song for high-performing male vocals. Pavarotti is the greatest classic singer maybe ever. Fight me!
Iron man - The sound at the beginning is hard to make sound great, great drums, and cymbals, and if done right it feels like an old-school band.
I Will Survive (1981 recording, I like her voice, and the old vocals, the drums, and various natural instruments really make this a favorite for me.
There is a light That never goes out - Smiths ( A classic, I just love it. It’s mellow, and I can tell a lot of the tuning if this song is done right.)
Jump (I like how the sound effects are in this!)
Star Child Someone recommended this song to me, and I like how funky it sounds and has nice vocals and a mix of music and things going on.
Dicke Titten Ramstein The beginning is amazing and the bass hits hard. Great song. I love rock and metal. The German language fascinates me
Master of Puppets: Very fast song. Helps me determine if the driver can keep up.

This is a newer version of my 10 favorite songs that also work for audiofile music.

This is a copy of a bunch of good audiofile music. Some are on my favorites, but all are great to test headphone tracks. (70+)

This is my favorite overall music. 300+ songs (needs to be edited a bit)

Bass (20-60 Sub Bass, 60-250 Hz Mid Bass)

The details of the bass is good and impactful. It hit right where I’d want it to. I found it dynamic strong and fun. One thing this iem isn’t is lean, although the sub-bass is a little low for my liking.

Midrange (250 HZ to 800 HZ Low Mids, 600-2000 Hz Mids, 2000-5000Hz Upper Mids)

The midrange is very unique. It has a recessed lower mid, and the upper mids are very nice.
This sounds good with podcasts but on occasionally vocals are a little recessed and not as smoothe as I might wish. But overall it’s solid

There is no shout from this iem, and to me that is huge. I love the upper mids. The lower mids, not so much. The upper mids are nice, non shouty and down right fully enjoyable.

Treble (5000- 10000 Trebble/Highs, 10000 ++ HZ Upper Trebble & Air)

The 5-6k region which is still fairly accurate on a 711 coupler is very hot for me. This might be an issue with some people. I prefer sets that have this down a lot more. Is this an issue, no in fact in just reviewed a set that had a peak around that level. But for what I am used to the 5-6k region comes across very bright.

The treble is a good part of this set and this iem has great detail and sparkle for me. No issues here. I’m able to game, listen to music, and a podcast all at once with this iem. It has incredible details that come across in the treble. Looking at the frequency response I would think it would sound neutral or boring without the 3k spike, but I enjoyed it. All the music that I listen to sounds great and I feel that it has a wide beautiful soundstage. Lots of sparkles and air for me. I fully enjoy this tune despite it being a little bit much in the upper air.


Gaming is great on this iem, it’s cozy and has a world-class feeling of fit to me. This to me is more of a music-tuned iem. I personally enjoy it, but It doesn’t get my full recommendation for competitive gaming. I think you might find better value for a lower price. But I see no reason why this couldn’t be a great set depending on the game that you were playing. Tuning for gaming is a bit of a meme.

Shell -
The shell is pretty, it fits great and I find it an exceptional fit. This has one of the best fits for my ear that I’ve ever had. The shell is very world-class, and has good isolation.

Case- The case feels great in hand. I like the size of this case being small, but having a zipper. It reminds me a lot of the Theiaudio cases. It looks great and feels good in hands. No issues here. This one of the nicer cases that I have had the opportunity to try, I really like the zippers on it!

Cable- The cable comes with both a 3.5 or 4.4. I like this cable and find it to hit all the marks that I would want for a cable. It’s thick, premium feeling, and beautiful. What else do you need?


Tip Selection - There is a wide variety of tips for this iem. I mainly tested with Divinius and had no issues.


Vs Kiwi Ears Forteza

I kinda liked the Forteza, but it sounded very sharp on a lot of music to me. The vocals didn’t work. Something about it was off for me. It was very sibilant.
The upper air in the Relentless iem really works for me, and I am a huge fan of its unique tuning. It has a bit of extra energy in the upper mids that I don’t like, and a fall off in the treble.

Vs Other Kinera offerings.

I think this is easily my favorite iem from Kinera that I’ve reviewed. The Phoenixcall and Dark Phoenix had a lot of 1.5k shout for me. The Plutus beast had a lot of 2k. The Relentless has great upper mids. Again, this is my favorite Celestee product that I’ve tried personally. Not just sonically, the cable, the design, the included case, are just all very class. It is more expensive but in this case I feel the packabing and superior shell almost justifies that increased price.

Vs KZ Symphony

The KZ Symphony is a V-shaped iem, but it wasn’t effective to me. It didn’t have a great flow. To me this is a much stronger V shape and a lot of fun. It was a good attempt, but I fear maybe something was off in the manufacturing or something. It just didn’t work for me at all.



Sound - Final Impressions

While this iem is very good, and I personally find great enjoyment out of it, I do fear our Harmon lovers might not love this. For those who look at graphs and are concerned, I would share your opinion as a Graph sniffer myself. But as someone who has got to experience this. I would recommend highly, like very highly to put this iem on your demo list! I fully enjoy this tuning and think it’s a treasure at its price point. It’s a good unique, and I love how Kinera/Celestee will keep doing new and different tuning. This to me is a treasure at the price and one of my favorite iems, that I’ve been sent ever as it is so unique.

But again, all my opinions are based on my ears and your mileage might vary.

Recommended EQ: I use Peace APO to EQ on the PC. This EQ is done to my preference. I recently set up a preference curve on My Squig. So for at least iems, I can use my own graphs now. Please feel free to use the measurements as you want..
Overall this is a strong iem, that I enjoy with no eq.

Preamp: -2.9 dB
Filter 1: ON PK Fc 21 Hz Gain 1.9 dB Q 0.500
Filter 2: ON PK Fc 110 Hz Gain -1.5 dB Q 0.700
Filter 3: ON PK Fc 230 Hz Gain -0.8 dB Q 2.000
Filter 4: ON PK Fc 600 Hz Gain 3.1 dB Q 0.800
Filter 5: ON PK Fc 12000 Hz Gain -6.8 dB Q 0.500
Filter 6: OFF PK Fc 0 Hz Gain 0.0 dB Q 0.000
Filter 7: OFF PK Fc 0 Hz Gain 0.0 dB Q 0.000
Filter 8: OFF PK Fc 0 Hz Gain 0.0 dB Q 0.000
Filter 9: OFF PK Fc 0 Hz Gain 0.0 dB Q 0.000
Filter 10: OFF PK Fc 0 Hz Gain 0.0 dB Q 0.000

Gifting/who is it for: I think this is a nice hifi iem to gift to someone, it is an expensive iem but overall it’s a solid package that sounds fantastic. It’s a handsome shell, good-looking cable, that is well accessorized.

I think this is a nice fun tuned iem. In a world of a billion, Harmon tuned iems it’s nice to have something fun and slightly different at a strong price. There is different and bad, then different and fun. To me and my ears, this is different and fun.

Pairing: I used a Quidelix 5k for mobile, my dongle Dac iBasso DC04 for my laptop, and my JDS labs Element III MK2 Boosted for my Desktop PC. I also tried the iem briefly on the Apple dongle as well. This iem had no issues being driven. Typically I only find overears to really have a hard time being driven and maybe some planar iems.


I find this a fun competitive iem at a price for those willing to try a unique experience and like a tactful V shaped iem with great technicality and resolution. I just dig this iem, and have no problems recommending with the multiple caveats that I’ve discussed. My philosophy is to always demo products. This one is a fun, well done V that has good details and it just works for me in a strange way. Now I’m going back to the Relentless. :)

Thanks for reading, and maybe even watching. Any feedback is welcome.

Youtube link below for those interested.

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