Planar drivers typically drink power whenever they can and the S12 is not an exception to the rule with its 16Ω and 102dB SPL efficiency rating.

Landing in a very similar volume setting with the Raptgo Hook-X, I had the 1.8W Topping DX5 set at -47dB for my normal listening volume for the S12. With the Sony NW-ZX507 DAP, it evened out as well right in the middle at 50% loudness.



For a more truthful profile of the S12, I had it first paired with the DX5 for a quick listening session. Its lean sound profile especially in the higher frequencies doesn’t help with the thin and sometimes hot treble region of the S12.

Going for a warmer source, the NW-ZX507 did give the S12 kinder treble energy combined with added weight in cymbals and horns.

While it has a smaller object presence, its stronger appeal towards the midrange brings back some soul in ballads not present in the DX5. Finer textures also sound more refined with the NW-ZX507, and depending on your taste, its wetter bass presence with a stronger mid-bass punch is quite graceful.

HiBy Lasya Review

Select Comparisons

HiBy Lasya



Both with lone driver units, the Lasya went more conventional with a 10mm dynamic driver for a similar frequency range of 20Hz to 20kHz. During its development, Hiby went full throttle to give the Lasya a midrange tuning worth its higher price tag.

What gives the Lasya its signature presence is the custom-like shell shaped after real-world scans of ear canals and concha. While it will not replace a personalized IEM fit, its better comfort and snug fit give it an edge over the simpler housing of the S12.

Pentaconn Ear sockets are also featured in the Lasya which are more modern and more reliable on paper than the standard 0.78mm 2-pin sockets of the S12.


Some users will appreciate the simpler shell of the S12, but the likable transparent resin of the Lasya with its tailored faceplate will be more suitable. This also makes venting routes and drivers all visible when checking out the Lasya.

While there is not that much to complain about with the comfort of the Lasya, Shuoer went further by offering their S12 with a cable relief system extending the cable connections outside the main shell for a more ergonomic wearing style.


Having a leaner presence in the bass region, Lasya is proving its ‘less is more’ approach by letting the midrange shine yet being careful not to get drowned out in the process.

The immense energy of the S12’s bass does lift subtleties more readily pushing it ahead of its neighbors. The cleaner and direct profile of the Lasya extend just as well but rely more heavily on the initial punch making it less immersive for bass-heavy passages.

Serving as the main dish for the Lasya, vocals get stronger and more refined in character which is ideal for creating naturally raspy and soft female singers. Its more resolving and forward midrange also gives the Lasya an intimate and enjoyable flavor to songs.

While the S12 is quite timid in instrument details such as the piano, the richer nature of the Lasya improves on timbre but also in reverb and textures. Guitars similarly get extra room information with the Lasya, though it has the same relaxed zing as the S12.

Cymbal delineation is stronger in the Lasya all the while having a similar splashy attribute as the S12. Brass instruments seem controlled and better isolated with the Lasya compared to the more energetic and lively representation of the S12.

With less bass dominance, the Lasya will return a more confident image placement, especially around the lower frequencies. Stage width in both is quite close but more space can be heard with the S12 for depth giving it the slight advantage in live recordings.

Raptgo Hook-X Review

Raptgo Hook-X



The Hook-X has an extra pair of drivers in the form of custom PZT modules that will add some additional headroom to the presentation. The 14.2mm main planar drivers of the Hook-X may be smaller than the S12 yet it is more proficient in extending the higher frequency range going up to 40kHz.

Raptgo went all out with the Hook-X as they did not stop with just combining two unique drivers in a single shell. For a truly fresh take on IEM design, the Hook-X is not just a hybrid IEM, it is also using an open-back system allowing the drivers to breathe, relieving ear pressure.


Both IEMs are universal but claim improved wearing comfort having formed their shell after real-world models and experiments. The bigger case of the Hook-X though achieves this better having a more even weight distribution against the more bottom-leaning S12.

Physically, the S12 will more likely appeal to those looking for a pair of monitors that will go under the radar. The featured polished beveling in the S12 gives it a touch of elegance but is still overall simpler contrary to the bolder spearmint inserts and opened faceplate of the Hook-X.


Both can offer a good quantity of bass to those who have an affinity for warmer sound signatures. The difference lies in the tighter body and punch of the Hook-X against the fuller and more involving thumps of the S12.

Having a broader presence in the lower region, details in the S12 get pushed forward making it sound more textured but the Hook-X is not too far off with some nice definition and generally a tighter performance. 

The open-back nature of the Hook-X plus its wider frequency range does translate to an airier and more resolving experience. Vocals disperse more freely and are more relaxed in the Hook-X. This translates to piano and guitars shaving away some shimmer and performing prudently in the background.

The Hook-X also gives a sweeter and fuller violin timbre which competes against the more vibrant quality of the S12. It is definitively better at creating a holographic stage with its taller and open-sounding soundscape, unlike the more boxed-in placement of the S12.

Hidizs MD4 review

Hidizs MD4



The Hidizs MD4 has four balanced armatures reaching between 20Hz and 40kHz. It is designed for a cohesive listening performance with a 3-way crossover and a straight acoustic sound tube eliminating interference between the drivers.

Making the MD4 more customizable with the possibility to change its tuning out of the box, is the availability of two dip switches. Depending on the configuration, users can select between four listening profiles.


While the MD4 can also be bought in indigo and black, comparing the white ones against the S12 reviewed here inspires a similar sense of minimalism. Still, the amber faceplate finish of the MD4 in addition to its gold inlays gives it a more premium tone especially when the mirrored finish of the S12 begins to scratch.

Both IEMs use aluminum alloy in the rest of the body. By the top where there is a huge vent for pressure relief in the S12 are the switches allowing the selection of different tuning flavors of the MD4.


Between the two IEMs, the MD4 comes with a more colored profile extending throughout its frequency range. This makes the S12 the more accurate monitor with the exception of the bass region wherein it shares a similar warm coloration.

The punch and slam of the MD4 are faster when compared to the low-end energy the S12 carries. But for details, the S12 still wins by a wide margin, since the MD4 lacks in bite and sub-bass texture.

Less lean than the S12, the warmer midrange of the MD4 is also recessed but does not pair as well with distinctive female vocalists as it develops a strange pitch. Both give less emphasis to the piano reverb, but the MD4 is edgier in detail retrieval.

Horns and violins disperse softly with the MD4 but are not as alluring as the S12 in timbre as it tries to be pristine but falls behind in depth and character. The S12 also images better laterally but the MD4 will let users hear farther toward the front.


Our Verdict

The modestly priced LETSHOUER S12 can justifiably compete with its satisfying vocal timbre and considerable low-end energy, offering a warmer tuning within a compact and spirited setup.

Even though it trades away some details and cohesion in the bass region in exchange for size, the drivers do react well to the source making it flexible for when the treble response gets a little too excited.

For its debut, the custom planar drivers used by LETSHOUER have some good promise. It confirms the capacity of this technology to become a multi-driver design of choice for portable devices.

LETSHOUER S12 Technical Specifications

  • Type: Planar Driver IEM
  • Color: Silver / Gun Metal Grey
  • Plug: 0.78mm dual pin
  • Sensitivity: 102dB
  • Impedance: 16W
  • Weight: 12±3g/pair
  • Cable: Silver plated monocrystalline copper cable


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