Beautiful transparent shells with innovative pressure-relief, Spectacularly accurate timbre throughout, Hugely resolving midrange, Fast and extended BA bass with tasteful emphasis, Flat impedance design is easy to drive
Dainty stock cable, Limited accessories, Treble doesn’t have much energy or sparkle
Combining hugely impressive timbral accuracy with top-level resolution, the RS10 provides a sound that has surely secured itself as a benchmark for years to come.
Moondrop is the name on everyone’s mind but their premium division, Soft Ears, are far less frequently discussed. This is not for lack of expertise nor success, as the company has only just recently expanded into the international market. I previously reviewed the RSV that I found to be one of the most impressive monitors on the market, a beautiful showcase of the company’s mastery of tonality. The RS10 builds upon the same reference sound platform and is currently the top model in their reference line alongside being their latest flagship. It houses a huge number of technical innovations and offers superb tonal refinement, taking the knowledge and technical expertise of the company to its pinnacle. Of course, its intended use case as a reference monitor should speak volumes for the type of sound tuning one should expect.
The RS10 is currently available for $2099 USD. You can read more about it and treat yourself to a set on Soft Ears.
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.
- Drivers: 10x BA drivers per side + 1x passive BA
- Crossover: 15-component, 5-way
- Impedance: 25 ohms
- Sensitivity: 100dB
- Frequency response: 20 Hz – 40 kHz
Behind the Design –
Custom Drivers With 5-Way Crossover
In addition to sporting a prolific 10xBA drivers per side, Soft Ears leveraged custom drivers as well that enable them to hit a more specific frequency response target and distortion characteristics. More drivers mean more complexity, so such a setup doesn’t guarantee a better sound, but theoretically has the ability to sound much better than a lower driver count if properly executed.
Of course, Soft Ears have implemented many techniques to optimise the sound output of the RS10, and this is a hugely well-considered design altogether. A 15-component, 5-way crossover has been used in order to achieve their desirable frequency response. Soft Ears take this one step further by tuning the time domain achieving almost linear phase across its 10 drivers. This was achieved using 2 band pass, 1 low pass and a 4th order LC filter.
Passive Driver + Pressure Relief
There are many challenges when designing in-ear monitors, one that is becoming increasingly spoken about is pressure relief. 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 have used a unique approach, using a passive 11th BA driver with no motor structure. This allows the 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.
Ultra-Low Impedance Fluctuation
Another common weakness of in-ear BA design is their sensitivity to source output impedance. Soft Ears designed this earphone to have an almost flat-impedance curve, enabling a consistent sound across sources with differing output impedance. This is a great tool for professionals especially where interfaces may have a higher impedance. It means you reap the benefit of BA-driver efficiency without the touchy source pairings.
There isn’t much to say about the unboxing experience and it appears not to be of highest priority here. The buyer receives a small hard box containing a round leather case. Insides are the earphones within suede pouches that keep them pristine during shipping. A microfibre cleaning cloth is just below. The cable and ear tips are in a separate box, you get 3 pairs of silicone tips tuned to the fit-depth and nozzle size of the RS10. I did enjoy the tonality and seal of these tips and used them for this review. Otherwise, the buyer receives a nice metal Soft Ears business card but no other accessories. I am not personally bothered by this, but I can understand some wanting a more lavish experience from such an expensive product
While we’ve seen no shortage of 3D-printed clear shells pop up lately, the quality Soft Ears was able to achieve is mind bogglingly good. Even pixel peeping macro shots on the RS10 reveals zero bubbles or contamination. While one could argue for a premium metal shell at this price, the solid-body resin shell here is a thoughtful showcase of the earphone’s inner beauty; the 11 balanced armature drivers, four acoustic chambers and 15-component crossover mean the earphone is just as much of a pleasure out of the ear as within. With a transparent shell, Soft Ears’ design and workmanship is on full display, rarely do I see such a high level. The design cues also draw a parallel with the transparency of its sound as a reference monitor, altogether a smart design with perfect execution.
Above are 0.78mm 2-pin connectors lauded for their ubiquity, permitting wide aftermarket support. The stock cable is of pleasing quality and is similar to those you’ll find on the latest Moondrop IEMs. It’s a silver-plated copper unit with super-high strand count and clear jacket. It has an internal braid which means you get a little more microphonic noise but nothing excessive due to the over-ear fit. The cable is very soft, my main complaint would be that it’s a little thin above the Y-split. Otherwise, it impresses with its chrome connectors with laser etched Soft-Ears logos and thin, case friendly 3.5mm plug with strain relief.
Fit & Isolation –
The RS10 has a similar silhouette to the previously reviewed RSV making it slightly squatter than Moondrop’s resin earphones. The RS10 is identical in shape to the Cerberus meaning it has a slightly wider and more squared off shell relative to the RSV. It remains very smoothly formed, creating a snug fit but without excessively sculpting the anatomical features to maximise compatibility with a wide range of ears. In turn, I found them comfortable to wear for hours on end with no hotspot formation. The nozzles are of medium length so the fit depth isn’t too deep, remaining quite comfortable.
As the nozzles are well-angled, I achieved an excellent seal and rock-solid fit stability. Combined with the dense resin-filled shells and fully sealed design, the RS10 provides excellent noise isolation suitable for loud environments. The pressure-relief passive driver does also improve the experience here. It does indeed alleviate some wearing pressure well, and you will notice this in daily use through a more comfortable wearing experience, especially over longer listening, and less “thud” from footsteps when listening during commute. I was surprised how effective Soft Ears solution was as it comes with zero compromise to isolation or seal.