Celest Relentless

MatAudiophiles

KINERA CELEST AUDIO RELENTLESS​

KINERA CELEST AUDIO RELENTLESS
INSTAGRAM: LINK
Prelude:
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.

Sound:
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.

Comparisons:

CELEST AUDIO RELENTLESS ($169) VS CELEST PHOENIXCALL ($129)
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.

CELEST AUDIO RELENTLESS(169USD) VS KINERA IDUN 2.0(169USD)
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 ($169) VS SOFTEARS VOLUME ($289)
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.

Summary:
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.

Introduction​

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 HiFiGO.

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

Packaging​

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).

Cable​

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.

Sound​

GEAR USED FOR THE TEST

• 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.

Lows
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.

Mids
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.

Highs
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.

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.

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:
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.

Conclusion:
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.