Soft Ears Cerberus Review – Analogue Reimagined

Sound –

Testing Methodology: Measured using Arta via IEC 711 coupler to Startech external sound card. 7-9KHz peaks may be artefacts/emphasised due to my measurement setup, less so with deep fit. Measurements besides channel balance are volume matched at 1KHz. Fit depth normalised to my best abilities to reduce coupler resonance. Still, due to these factors, my measurements may not accurately reflect the earphone or measurements taken by others. I gave the Cerberus 100hrs of burn-in prior to subjective review to ensure maximum performance.

Tonality –

The Cerberus is an odd beast, not an earphone that you listen to and think WOW, but one that is completely non-fatiguing and surprisingly resolving. I say this because there’s nothing wrong with its tonality, but it does require acclimatization – relative to most high-end IEMs that is. Coming from a bright and revealing earphone like the Fir M4, the Cerberus just sounds dull and dark. Coming from a U-shaped model like the U12t and you’ll find the treble hazy and ill-defined. But spend some time adjusting, and the fine details are apparent, just less aggressively presented. The execution of the tuning also grants the Cerberus qualities that you won’t find replicated elsewhere.

The signature is superbly even-handed, well-integrated and highly natural, but at the same time will not appeal to those wanting huge separation, power nor clarity. The appeal of its presentation draws from two pivotal strengths: its liquid, delicate note presentation, and the superb cleanliness of its background that serves as an immaculate canvas. These two qualities work in tandem to deliver an impressively immersive image that equally values fine details in the background as those set out more readily before the listener. Though no note jumps out with bite or snap, the listener is better able to appreciate fine nuances such as the space surrounding each element and the rich textural qualities of each instrument. Indeed, this is a sound that takes some time to appreciate but has formed an experience that I find no less rewarding than any other high-end IEM in my collection.

Tip Choice

Where I felt the stock tips sounded great on the RS10 and RSV, I did find the Cerberus is more tip sensitive and required some rolling here. The Cerberus is already on the smoother side so I found brighter tips with a larger bore to be a good pairing. I especially enjoyed the Azla Sedna Fit short tips. They provided noticeably more bite in the treble and a bit more overall detail and openness and I preferred their soundstage presentation too. Azla’s Xelastec tips are also not a bad choice but skewed brighter and didn’t provide the bass pressure I desire; these may be good for treble heads. I also enjoyed JVC Spiral Dots that provided similar changes and a bit more comfort, these will be better for those wanting a bit more openness but more warmth than the Sedna fits. While Final E-tips and Spinfit CP100+ fit fine, I did find them to lack some midrange presence by comparison.

Bass –

The low-end performance is very interesting on the Cerberus; a combination of a superbly clean, progressive sub-bass boost and tight yet smoothly textured note presentation. Emphasis climbs linearly from 1kHz into the sub-bass with zero roll off. If that sounds familiar, it’s because the tuning is identical to the Etymotic EVO that I also lauded for its excellent bass tuning. However, do not mistake this for a lean or bass light earphone as the Cerberus has less midrange emphasis, and the dynamic driver provides more extension and oomph. The Cerberus sounds perfectly balanced and delivers an almost lifelike timbre. If you love an achromatic tonality with a tasteful bump in sub-bass weight, this is a terrific example. This is also in stark contrast to the majority of high-end hybrids that pursue a more engaging tuning with firmer sub-bass pressurisation.

The Cerberus has what I would describe as a smooth and free-flowing note presentation, perhaps owing to its exceptionally lightweight yet not especially rigid diaphragm material. It is low pressure in the sub-bass and has a softer attack and a neutral decay. Thus, dynamics and outright note definition are not its forte. This earphone is characterised rather by its highly articulate and textured nature. For though notes aren’t assertive nor hyper defined around the edges, control and responsiveness is top level. The mid-bass is superbly textured, and bass has both excellent separation and organisation. Coming from something like Empire Ear’s Weapon IX driver, one may find the hybrid setup here missing some drive and authority. However, spend some time adjusting and you’ll find the Cerberus is tonally outstanding and a master of texture and control.

Mids –

Though built atop a similar foundation, the Cerberus serves as the coherent, musical foil to the lean, maximally resolving RS10. Indeed, the Cerberus trades some resolution and definition in favour of greater smoothness, body and overall structure, with which it excels. This starts in the lower midrange which enjoys a hint of emphasis that provides a great foundation for a presentation that places equal emphasis on all kinds of vocals and instruments. In addition, pinna gain is reduced by just a few dB with a slight 4kHz bump reintroducing clarity and openness. As the midrange on a whole doesn’t sit too forward, the Cerberus lacks any form of intensity or thinness. It has a hint of full-bodied character, enough to instigate a coherent character, but never to the detriment of separation or organisation. The Cerberus has excellent layering, a winning balance between foreground focus and the room and space surrounding. It’s, to me, the background that allures most on this earphone. Notes gently fade in and out giving it a very immersive quality.

Clarity is increased just a smidge over neutral but is reined in by a silky-smooth articulation. In turn, some may find the Cerberus is lacking a lick of definition in the midrange. It has a softer note attack in the treble as seen on most EST models, and a smoother lower-treble tuning on top. However, if you enjoy a refined, mature and highly layered image, the Cerberus cannot be faulted. Like the bass, it represents a masterful understanding of sound tuning combined with what appears to be a deliberately smoother note presentation. The cleaner tuning ensures separation is maintained and the overall linearity and balance once again work much to the benefit of timbral accuracy. At the same time, the Cerberus has a soft, analogue character to it. While this means it isn’t hyper defined and revealing, this is not to be mistaken for a technically inept earphone due to its perfect organisation and excellent imaging performance. The Cerberus is a highly natural and organic earphone yet simultaneously an immaculately clean one.

Highs –

As far as tuning goes, the treble response errs on the smooth side on the Cerberus and the signature reflects that of Sonion’s reference material well. That means you get a smoother lower-treble region with a peak at 7kHz and great upper-treble extension albeit not too much brightness in these regions. In so doing, the Cerberus isn’t the most immediately impressive high-end IEM to listen to. Treble lacks that hard edged attack of many competitors, similarly, though extended, sparkle isn’t overtly apparent. Soft Ears were able to tease out a reasonably coherent sound out of this driver setup, that said, and I found instruments impressively well-bodied and textured for an EST earphone. Though still on the delicate and dainty side, the Cerberus has a natural decay and sound note weight and body. It lacks the tizzy, over-tone dominated sound that many others lesser EST implementations succumb to. Meanwhile, the EST benefits are maintained and exemplified; that being, wicked background cleanliness and excellent note speed and separation.

Again, you don’t get the crispest lower-treble nor the most defined leading edge, but a natural, clean and textured treble just slightly laid-back relative to the mids and bass. Still, treble instrument timbre impresses and there’s ample presence to engage. Similarly, the Cerberus does have impressive amounts of air and headroom above meaning, though the background is clean and dark, it doesn’t sound closed off and detail deficient nor overly smoother over. These qualities contribute greatly to its imaging performance, its excellent layering especially. The beauty in the presentation isn’t the overt resolving power and definition nor its engaging tuning. In so doing, this isn’t the most instantly gratifying sound, but a highly atmospheric one. It’s the sense of refinement and background cleanliness upon which fine details pop more than most that truly immerses. It does so with zero sharpness, brightness or grain of any sort, permitting a beautifully smooth ebb and flow of music.

Soundstage –

Here, the unique qualities of the Cerberus truly come together into one coherent whole. The soundstage is overtly spacious in all axis but with a moderate width bias. It extends well beyond the head and has an almost holographic quality with regards to imaging; achieved not through sparkle and brightness, but speed and cleanliness. The background is highly resolved, which combined with its linear, structured tuning, gives the Cerberus outstanding layering and organisation. Localisation isn’t as sharp as on the RS10, preferring looser direction in favour of greater atmosphere and dimension. Separation is excellent, notes are well-delineated even on complex passages and there is palpable air and space surrounding each. However, this is in a different sense to the RS10 where each note is more defined, thereby being more separate from one another. The Cerberus is surely a more coherent and integrated sounding earphone by comparison. It can’t slice through mixes in the same way but does impress with its overall composure and organisation. Vocal harmonisations especially are presented beautifully, elements such as backing vocals fade in and out of the image with exceptional smoothness.

Drivability –

The Cerberus has a 104dB sensitivity and a very low 5-ohm impedance with no mention of a linear impedance curve. This means source pairings will be essential for this earphone.

Output Impedance Sensitivity

Switching between the Shanling M2X (1-ohm) and Hiby R6 (10-ohms) revealed that the Cerberus does sounds best from a 1 or even sub-1-ohm source. Bass was diminished on the R6, producing a brighter sound with a diminished midrange. That said, even a 1-ohm source will provide an ideal experience with regards to tonal balance, the rule of eighth’ doers not apply in its entirety here.

Driving Power

The Cerberus actually doesn’t require a lot of power to achieve a controlled and expressive sound. Switching between the M2X and my desktop stack with THX789 and SMSL SU-9 revealed minimal change in bass control or dynamics. This appears to be a very efficient design that sounds great from many sources so long as the output impedance is low. While the soundstage and resolution do scale nicely, a balanced and powerful listen can be achieved even from a smartphone or dongle. In addition, sensitivity is not so high that it is hiss prone, for instance, on volume 0 with the amp circuit on using the M2X, no noise was audible.

Suggested Pair Ups

Given the high but not excessive efficiency and low impedance, the Cerberus is a very easy IEM to drive, output impedance being the only consideration. So long as it is 1 ohm or below, you will have an honest representation of music. As tonality is such a large focus for this earphone, I found this earphone paired beset with a neutral source. I enjoyed Topping’s higher-end models in addition to the THX789. The THX amp, in particular, provided a slightly more dynamic bass and a sharper treble attack that complemented the Cerberus’ smoother nature well. For those wanting to maximise the analogue qualities of this earphone, a smoother setup like the A30 Pro + D30 Pro stack is a winning complement, but I did enjoy having a bit more definition personally.

Next Page: Comparisons & Verdict



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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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