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Soft Ears Cerberus Review – Analogue Reimagined

Pros –

Superb smoothness, Exceptionally clean background and tone, Highly textured bass, Immersive and spacious soundstage, Highly natural timbre, Easy to drive

Cons –

Lower note definition, Laid-back top-end can make it sound dull relative to most high-end IEMs, Not the most engaging sound altogether

Verdict –

Should you enjoy a balanced and spacious sound with excellent control throughout, the Cerberus makes for a unique and immensely rewarding listen and continues to surprise after every hour of listening.

Introduction –

You’ve heard the spiel, Soft Ears is the premium division of the highly coveted Moondrop who just recently made their international debut. And, what a debut it has been! With the RSV, RS10 and Cerberus leading the charge. If you’re here, you’d have likely come across their reference monitors in some manifestation; both are considered to be some of the best acoustic designs on the market, a sentiment I would personally agree with. The Cerberus is far less discussed. This is model targets a more musical sound and employs an equally sophisticated tribrid setup to realise this. Perhaps some are wary as this model was the company’s first flagship and an early EST implementation. However, a first product often makes or breaks a company and, therefore, needs to make a statement. The Cerberus is not a cheap earphone, but it is a hugely technically advanced one. While any manufacturer can grab some Knowles drivers and slap on an electrostatic tweeter array, Soft Ears have taken careful steps to optimise the sound at every turn. Soft Ear’s triple-headed beast is, undoubtedly, a creature of maturity and refinement.

The Cerberus is currently available for $2099 USD. You can read more about it and treat yourself to a set on Soft Ears.

Disclaimer –

I would like to thank the team at Soft Ears very much for their quick communication and for providing me with the RSV, RS10 and Cerberus for the purpose of review. All words are my own and there is no monetary incentive for a positive review. Despite receiving the earphones free of cost, I will attempt to be as objective as possible in my evaluation.

Contents –

Specifications –

  • Drivers: 1x DD, 4x BA, 2x EST
  • Crossover: 3-way
  • Impedance: 5ohms
  • Sensitivity: 104dB
  • Frequency response: 20 Hz – 40 kHz

Behind the Design –

Custom BA drivers

Image courtesy of Soft Ears

Leveraging their relationship with a prominent BA manufacturer in China, Soft Ears were able to design their own BA drivers for the Cerberus in addition to their other models. It is an unconventional all-in-one quad-driver unit. If optimally implemented, this would cut distortion down to a quarter of a single BA driver. By designing the driver themselves, the company is granted more control over the frequency response and time response of the drivers. This allows for smoother crossover points and a more coherent overall sound in the context of a tribrid driver setup especially.  

Passive Driver

Image courtesy of Soft Ears

Like the RS10, the Cerberus implements a passive balanced armature driver with no motor circuit for pressure and fatigue relief in addition to enhancing the perception of bass texture. To quote my RS10 breakdown, increased wearing pressure is an especially large issue with in-ears as they form the tightest seal with the ear canal. This can alter the perception of sound over time via the tympanic reflex that results in decreased sound transmission to the inner ear – effectively reducing the perception of dynamics, bass and treble and resulting in a much less resolving sound.

Competitors append this using valve or membrane which relieves pressure at the cost of isolation and bass slam. Soft Ears’ approach rather allows the passive driver’s diaphragm to move freely and dynamically relieve pressure from the ear canal. In addition, it serves to enhance the driver surface area available, pertinent for bass response. This is a very clever approach as there is no drop in isolation or seal and you get an overall more efficient sound reproduction system. 

Proprietary Dynamic Driver

Image courtesy of Soft Ears

Soft Ears designed a 10mm dynamic driver that is exclusive to the Cerberus and sports a few interesting qualities. While the mechanical properties of the diaphragm have been the point of focus as of late, Soft Ears have assumed a more holistic approach to design. This driver uses a carbon fibre + paper dome. Paper is commonly seen in cheaper earphones as it produces a light and efficient driver at a low cost, at the expensive of rigidity and transient response. Soft Ears take this quality and enhance its mechanical properties with carbon fibre filaments.

This effectively reintroduces rigidity for reduced distortion and a fast transient response whilst upholding efficiency. A filter can be observed on the exterior vent, demonstrating that Soft Ears have tuned the back and front pressure of the driver to optimise the impulse response. They also tout a high-excursion with an elongated voice coil that should deliver more visceral sub-bass extension and higher dynamics. Great tuning from an engineering POV on behalf of the Soft Ears team.

Sonion EST tweeters

Image courtesy of Soft Ears

Sonion’s tweeters implement an ultra-light membrane driven by electrostatic force, offering one of the cleanest and quickest transient responses of all driver types. In turn, distortion is very low into the ultra-sonic frequencies delivering strong extension and resolution. They are, however, difficult to implement given the need for a high-voltage transformer that lowers their sensitivity, making pairing with other driver types difficult.

Taking a look at Sonion’s datasheet, the frequency response of their dual tweeter setup offers twin peaks at 4 kHz and 7 kHz, a trend that can be observed on the Cerberus too. This further complicates their implementation as bringing up treble response means simultaneously bringing up the upper midrange which can introduce odd timbral characteristics. Soft Ears here have prioritised the midrange timbre over imbuing the sparkliest and most energetic treble, for an altogether smooth and refined sound.

Unboxing –

The unboxing experience is identical to the RS10 just with a different colour scheme. You get the same non-frills compact box with slide out tray but with a soft-touch green exterior. Inside is a leather carrying case, also in a deep emerald green. As before, the case has a great in-hand feel, especially in green with a micro-suede texture. The interior is also suede which provides a softer surface that avoids scratching the shells. The earphones themselves come within separate pull string bags and a microfibre cleaning cloth is included below. A separate box beneath the case contains the cable and 3 pairs of silicone ear tips. It’s a very straightforward package and the tips as well appear carefully designed to limit fit depth to ensure a more consistent sound between listeners.

Design –

The Cerberus very much resembles the RS10 with similar dimensions and silhouette, but slightly more squared off edges. It trades that unit’s transparent aesthetic for an un-filled acrylic housing with a gorgeous gold swirl design. The superbly executed piano black is a flawless canvas upon which the gold particles really pop. Soft Ears has achieved a richness of colour and texture here that really complements the sound performance, much like the RS10. A filtered vent at the top of the housing is a reminder that this is a hybrid design. Similar to the other Soft Ears IEMs I’ve covered, though the construction is entirely resin/acrylic, the finish is flawless, with seamless faceplate integration and an immaculate gloss coat.

Up top are 0.78mm 2-pin connectors and, again similar to the RS10, they are non-recessed. The stock cable is identical to that on the RS10 too meaning the buyer receives a high-strand count SPC cable with internal braided design and super soft, clear jacket. Though supple, I did find the cable to be a little dainty, but sonically, I have found them to be a good complement for Soft Ear’s IEMs. The ear guides are soft and comfortable, the connectors are slim with a premium metal jacket, providing a sound haptic experience. While I would have preferred a nice stock cable, perhaps even similar to that on the RSV, they get the job done.

Fit & Isolation –

With similar dimensions to the RS10, expect a similar style of fit. That means you get relatively squat but wide housings and smooth sculpting that trades a perfect locked-in fit for greater comfort and compatibility with a wider range of ears. Being so smoothly formed with no hard edges, the Cerberus provides a comfortable fit and didn’t form any hotspots for my ears. The nozzles are well angled and offer a medium-depth fit, similar to the RSV and RS10, they are quite large but will suit flexible aftermarket tips such as E-tips, Spinfits and Sednafits to name a few.

Notably, the Cerberus is the only dynamic-driver touting model of the three I’ve tested and some driver flex is apparent when first inserted. It’s definitely not as prominent as on many DD earphones I’ve tried but was noticeable during testing. Otherwise, the vented housing does provide noticeably less wearing pressure than the sealed RSV and even the RS10 with its passive driver. The Cerberus too shares this feature, further contributing to a comfortable listening experience over long sessions. Despite this, wind noise isn’t exacerbated when used outdoors and isolation is almost as good as on the sealed models. This makes them a great choice for commute and even travel.

Next Page: Sound Breakdown



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Ryan Soo

Avid writer, passionate photographer and sleep-deprived medical student, Ryan has an ongoing desire to bring quality products to the regular reader.


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