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Celest Relentless: Relentlessly Fun

Disclaimer: I thank Hifigo for generously providing me with the Celest Relentless in exchange for an honest review. On behalf of the team at the Headphone List, we thank her for her generosity and trust in THL.


The Celest Relentless relentlessly adheres to an aggressive V-shaped frequency response with a boisterous, low-end, treble sizzle. While there are some noteworthy issues with timbral cohesion between the drivers, the aptly named Relentless is an exonerating listen in a market dictated by fleeting trends.


+ Beautifully painted faceplates.

+ All-or-nothing V-shaped signature with a lively and energetic presentation (complementary to genres such as pop-punk).

+ Very impressive imaging and lateral staging/width for an IEM.

+ Solid accessory pack.


– Resin-fabricated shells appear and feel ‘thin’.

– Noticeable ‘balanced-armature’ timbre artificiality

– Disjointed cohesion amongst the high-driver array.

– Bouts of sibilance and lower-treble glare.


Few progenitors in the Chi-Fi heydays have stood the test of time save for Kinera. Originally founded as Youtai Electronics in 2011, Kinera is a mature competitor with a decade-spanning tenure.

One of the first ‘halo products’ I had the opportunity to review in the infancy of my career was the Kinera Nanna. It was a remarkable product. From their striking designs to Kinera’s non-conformist tuning philosophies, Kinera is a senior brand appealing to a committed niche in the audiophile marketplace.

Celest is merely a trademark that falls under the ‘Kinera‘ umbrella. Dissimilar to its parent company, Celest’s designs deviate significantly from Kinera’s, opting for more stylized aesthetics and novel driver technologies for modest asking prices (you can read more in my positive review of the Celeste Gumiho).

Interestingly, Celest’s theming draws inspiration from the mythical creatures of Chinese mythology. I’ll have to brush up on my knowledge of Sinoculture and Orientalism.

Today’s review is a regression to the ‘standard’. Instead of contemporary ‘flat panel’ planar drivers, their latest IEM, the Relentless, returns to the tried-and-test hybrid architecture, boasting 6 customised balanced armatures and a single 8mm dynamic driver on each side.

Priced at $169.99, the Celest Relentless on-paper specifications are bound to raise eyebrows. But a specs sheet doesn’t tell all about its real-world performance: our ears do. The Relentless is available for purchase at Hifigo.


Multi-driver setup

The Relentless doesn’t reinvent the wheel but embraces it with open arms, featuring a hybrid-driver array of 6 Celest custom-balanced armatures, and a single 8mm moving-coil diaphragm on each channel. The entire frequency band is carved between them via a field-tested active crossover.

Bass and midrange duties have been relegated to the 8mm dynamic driver. Unencumbered by the bands above, 2 Celest Custom 29689 balanced armatures are tasked with the upper mids, while four Celest Custom 10012 balanced armatures are expected to produce crystalline and shimmery highs.

3D-printed cavities

Fully machined and fabricated from hypoallergenic resin, every shell is precision printed by Heygears.


The Relentless came shipped in a purple-haze-esque cardboard box with an outer sleeve. The Relentless specs can be found conveniently printed out on the back of the sleeve. Inside the box, you’ll find the following accessories package:

  • Celest Relentless
  • Saffiano-leather style hard case
  • 2-pin 5N SPC Cable (found stowed away in the hard case)
  • 3.5mm + 4.4mm interchangeable plugs (found stowed away in the hard case)
  • 3 pairs of S, M and L silicon ear tips with different ‘tunings’

The Relentless package offers users the usual fixings for daily use right out of the box.


The Celest Relentless’s silhouette follows the industry standard ‘acrylic’ mould, with a translucent oblong body, revealing the inner workings of the driver array. The entire chassis is 3D-printed and quality-tested by Heygears; a familiar name known for its stringent quality controls and flawless manufacturing.

Unsurprisingly, there are no physical or visible imperfections on each shell. The application of lacquer by the Celest team masks the seam between the hand-painted faceplates and shell.

On top of that, Kinara’s decade-spanning catalogue of IEMs all share one common design thread – hand-painted faceplates. Every faceplate is individually hand-painted by a skilful craftsperson for a visually striking appearance: a human touch that adds intangible appeal. In the instance of the Relentless, the wave-like swirl pattern in lapis lazuli is evocative of an oncoming wave on the shoreline of a serene beach.

Celest 100% deserves laudation for introducing users to this level of unerring standards and artisanal quality sans the excessive pricing.

Comfort and Ergonomics

My main criticism of the chassis pertains to its build quality rather than its spotless finishing. The resin mix used to fabricate the shells feels particularly thin, which doesn’t exactly instil confidence in its longevity over time. A thicker mould would have provided me with much-needed reassurance in its lifespan.

The upside to this is its ultra-lightweight footprint. Its featherweight chassis sits comfortably outside the concha without virtually any discomfort during my extended listening periods.

The nozzle (spout) length on each channel is moderately elongated, and its bore size is slightly narrow. Each spout is capped off by a wax guard in the form of wire mesh. Relative to my ear anatomy, each spout is adequately sized, laying comfortably in my ears with the provided ‘M’ sized silicon ear tips.

The Celest Relentless also performs favourably in noisy environments. Isolation against external ingress in urban environments is excellent, with barely any perceptible noise disrupting any of my private listening sessions.

Overall, the Relentless almost strikes a near-perfect score for the physical qualities I index for in this section.

Cable Quality

The Celest Relentless comes equipped with a 2-pin 5N SPC Cable. The cable comprises a machined-braided series of 8 strands of silver-plated copper (SPC), splitting into 4-braids per channel. The sheathing/jacketing on the cable is slightly rigid and inflexible, exacerbating the likelihood of unwanted memory retention. If you’re averse to unsightly bends and kinks, the Relentless’s cables aren’t going to do you any favours in that department.

Aesthetically, the cable is unmistakably silver-plated copper, with its characteristic inimitable lustre and shimmer. The Y-split and termination end are manufactured from mirror-polished stainless steel. While the all-metal hardware is long-lasting and hardy, steel is a dense and heavy material. Accordingly, the chin-slider’s weight pulls down on the upper half of the cable, accruing needless pressure on the outer earlobes when worn.

The cable also has swappable terminations, allowing users the ability to toggle between balanced 4.4mm and 3.5mm ends. To release the attached connector, users simply need to twist the termination cap in an anti-clockwise direction. Once complete, a solid tug is needed to remove it. To reattach another connector, users simply need to ensure the holes on the termination and cable-end line-up.

At $169.99, the inclusion of a swappable-termination system is an uncommon but welcome sight.

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Picture of Kevin Goh

Kevin Goh

Raised in Southeast Asia’s largest portable-audio market, Kevin’s interest in high-end audio has grown alongside it as the industry flourishes. His pursuit of “perfect sound” began in the heydays of Jaben in Singapore at the age of just 10 years old. Kevin believes that we live in a golden age of readily accessible, quality audio.


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