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Letshuoer S15 Planar Magnetic IEMs Review: A New Favorite

Christopher Coke Updated: Posted:
Hardware Reviews 0

Letshuoer has been a leading brand in the IEM space for quite a while and made quite a splash over the last year with its disruptive S12 planar magnetic earphones. What that product did for the sub-$200 space, the Letshuoer S15 is doing for the sub-$400 space. These IEMs have quickly become my favorite planar magnetic IEM for all of my listening, whether that’s gaming, listening to music, or even passing the time with Netflix. Comfort, detail, bass, tonal balance… these IEMs have it all. At $329, they’re on the expensive side compared to the S12 but are worth every penny.


  • Current Price: $329 (Letshuoer)
  • Key Features:
    • Third Generation 14.8mm Planar Driver + 6mm R-Sonic Passive Filtering Module
    • New Acoustic Structure, A Sound Quality Powerhouse
    • Dual Acoustic Tubes With Filter Crossover
    • Smooth Transitions Across The Spectrum And Rich Sound Layering
    • High-precision 3D-printed Front Cavity
    • CNC Precision Carved Aluminum Alloy Panel
    • Lightweight Ergonomic Design, Fine And Delicate Touch
    • 216-strands Silver-plated Monocrystalline Copper Cable
    • Detachable 2.5mm, 3.5mm, 4.4mm 90-degree Angle Connectors
    • 0.78mm Dual-pin receptacle
    • Practical Accessories
    • Every detail is implemented to contribute to the sound quality
  • Driver: 14.8mm planar driver + 6mm passive filtering module
  • Impedance: 30 ohms
  • Sensitivity: 106dB
  • Frequency Response: 20Hz - 40kHz
  • Cable: 1.2m 216-strand silver-plated monocrystalline copper
  • Audio Connectors: 2.5mm/3.5 mm/4.4 mm interchangeable connectors
  • Chassis Material: 3D-printed resin
  • Material of Faceplate: Anodized aluminum

Letshouer S15 - First Impressions and Key Features 

The Letshouer S15 is a planar magnetic pair of earphones, joining and now leading a class of IEMs that has exploded in popularity over the last year. Kicking into high gear with the 7Hz Timeless and running at a break-neck pace ever since, this section of the consumer audio market isn’t short on options. It takes a lot to stand out, which makes it all the more impressive how great the S15 is. 

Let’s begin with the packaging and presentation. Letshuoer did a great job with making this set feel premium and befitting its price point. It comes in a cardboard box that’s held closed with magnetic clasp and unfolds like a high-end gift-box. The IEMs are displayed proudly on the top, just below an envelope with documentation and a poster you can display.

The accessories are stored in a drawer that pulls out with a fabric tag. It reminds me of a jewelry box. Inside the drawer, you’ll find a dark blue carrying case and the three modular ends of its cable. Inside the case, the ear tips and cable are stored. The tips are presented rather uniquely on a ring, though I find that they fall off quite easily, so you’re safe to throw away the ring and just keep the tips. The tips are different colors and have different sized nozzles to slightly modify the sound of the IEMs. The white tips provide a bit more bass while the blue tips are more balanced and revealing in the mids and highs. Both sound great, though.

The earphones themselves use 3D printed baby blue shells with aluminum faceplates. There’s a neat triple-winged pattern that looks pretty cool without going as far into aesthetics as some of the resin shelled IEMs we review. No one is going to look at these an immediately assume they’re incredibly expensive and a prime target for stealing. That’s not a knock against the S15. They look good! But I do worries about theft are a real concern with expensive IEMs and these strike a good balance between looking good without being flashy in ways you don’t want. 

Internally, they’re have a lot of interesting elements to their design. They use the third generation of Letshuoer’s 14.8 planar magnetic driver (S12 was Gen-1 and S12 Pro was Gen-2). It has been refined and improved with each generation and this is easily the best iteration of the driver yet. It’s housed in a dual chamber acoustic cavity to enhance its soundstage potential and utilizes two acoustic tubes the company says helps to transition between the octaves, though I admit to being a bit unclear about how this is actually implemented with its single-driver design. 

This IEM also utilizes Letshuoer’s R-Sonic passive filtering module (PFM). Pre-release, there was talk within the audio community that this was akin to a passive radiator in a speaker, though that’s not actually the case. You can read more about it in the descriptions below, but in essence, this module includes a second diaphragm which vibrates passively as the planar produces sound. This vents out the inner face of the IEM, decreasing pressure and listening fatigue, while also cleaning up the sound a bit to reveal more details in the listening experience. 

Along with the IEMs, the cable is worth noting too. It’s a similar cable to what Letshuoer has shipped with the S12 and S12 Pro, but I really like it. It’s fairly thick, which means it has a bit more memory than I like, but it’s made with high-quality materials (216 strands of silver-plated monocrystalline copper) and has swappable terminations to match with different sources easily. It includes 2.5mm and 4.4mm balanced ends, as well as a 3.5mm single-ended termination. These friction-fit to the end of the cable very snugly, so you don’t need to worry about them coming loose and you don’t need to be concerned with plugging or unplugging anything.

Letshuoer S15 - Fit and Comfort

Comfort is one of the S15’s super powers — at least in my ears. In virtually all of my reviews, I remark that I need to use two different-sized ear tips to get the best fit. Even though this IEM is mid-sized, I was able to use a single size and have one of the most snug and comfortable fits of any IEM. The shells just nestled perfectly into my ears, allowing me to wear them for hours without any discomfort whatsoever. Fit is always subjective but these IEMs were truly excellent for me and I expect will be for many other listeners as well.

Letshuoer S15 - Listening Impressions  

The S15 isn’t a difficult IEM to drive, but like most planars, it benefits from having more voltage to drive its movement. With that in mind, you don’t need to go crazy with additional power. My audio interface and even my $15 CX80 USB-C headphone dongle drove them just fine. My laptop’s headphone jack made them sound slightly thin, however, so if you have something that can provide a bit of additional power, it will help them to sound their best. 

The tonal balance of these IEMs is really something special. As you can see in the graph above, they have a good boost in the sub-bass (rumble) that extends into the mid-bass (bass guitars, drums, synths, the body of explosions and gunshots), but flattens out in the mids so it doesn’t sound muddy. This rises again into the upper mids to bring out their exceptional detail, resolution, and layering. It’s a tuning that’s at once very fun and very revealing.

Put another way, the S15 really nails what planar magnetics are loved for. Excellent bass impact, resolution, and speed and outstanding detail, clarity, and layering. Letshuoer knocked it out of the park with the balance of these IEMs.  

Bass: Starting with the low-end, they really shine strongly. There’s more power in the bass than any planar IEM I’ve heard before, including the Tangzu Wu Zetian HBB HeyDey Edition and the 7Hz Timeless AE. It is the S15’s most defining feature. The low-end has excellent extension and tactile rumble. The blend between the sub-bass and mid-bass is exceptional, transitioning seamlessly, leading to an especially full, rich, well-textured sound. It’s also quick, which is typical of Letshuoer’s planar drivers. The bass hits hard and cuts off right as it’s supposed to, so it sounds clean and refined.

There isn’t a genre where this hasn’t been beneficial. Exhausted by Jonny Craig, Pandemonium by NF, Dawns by Zach Bryan, Wandering II by Eydis Evensen sound wonderfully full. Video game soundtracks and classical can sound downright cinematic when the drivers are given enough power and volume. The bass here is fun, refined, and excellent.

Mids: The mids are clear, clean, and detailed. Vocals have a very natural body to them and appear centered in the listening stage. Instruments also have a natural timbre to them with a solid body and crisp upper harmonics that “remove the veil” and make them sound detailed and lively. Acoustic and electric guitars really shine with this set. As a guitar player, I have an ear for specific details within the tone and effects line of overdriven guitars (oscillations within effects, the way notes ring out through gain stages, reverb, and compression, etc), and Angel Vivaldi’s Dopamine was very revealing and well defined. Strings and pianos have a similar quality.

For gaming, this range is exceptionally important. It’s where a lot of your positional information comes from, as well as key cues like footsteps and engines. The directionality and imaging is very good and is enhanced by the soundstage, which I’ll get to shortly.

Treble: The treble is well balanced for the tone of this set. If you look at the frequency graph, you’ll see the right side is a bit like a mountain range or saw blade as Letshuoer has tuned this to bring out detail while warding off sharpness and sibilance. I think it was a success. While I wouldn’t describe them as “airy” (that region of the ultra-highs has been tuned down), the treble tuning highlights a the detail and resolution strengths of this driver. It sounds exceptionally high resolution, though perhaps not more so than some of the best competitors, like the Timeless. Still, it’s very good.

Soundstage: The soundstage is quite wide, though isn’t class leading. IEMs tend to make it sound like music is coming from inside your head (which, well, it is) but the S15 brings that outside and into your room. It would likely be enhanced further with an open-back design like the Raptgo Hook-X (which is more expansive still), but the enhancement we receive compared to the majority of IEMs appears to be a result of the R-Sonic module. It’s good to see this enhancement has a noticeable impact as that’s not always the case with highlighted features on IEMs.

Gaming: The S15 is a great pair of IEMs for playing games. The deep low-end paired with the detailed mids and highs make for a very revealing gaming experience that is highly positional. You’re able to perceive where sources are coming from quite easily in games with great positional audio, like Battlefield or Call of Duty. Even if you’re playing single-player games, the tonal balance just makes playing games with these a lot of fun. They lack nothing compared to a full-fledged gaming headset other than a mic. This is a good example of where great stereo can trump virtual surround sound. If you need it, however, the S15 also plays very nicely with Dolby Atmos and Windows Sonic.

Overall Impressions and Final Thoughts

The Letshuoer S15 is an excellent pair of earphones. They’re on the expensive end but genuinely feel worth their higher cost compared to their predecessors and a number of other cheaper planars that are available today. The tuning really sells it, in my book. It’s much the same as the Fiio FT5 I reviewed earlier this week. The S15 delivers on more of the promises of planar magnetic drivers and does so better than just about all of the planar competition at this price and lower. If you’ve heard about how great planars are, the S15 gives you a great impression of what everyone else is raving about with fewer trade-offs. It is well worth considering for yourself or the audio-lover/gamer on your holiday shopping list. 

The product described in this article was provided by the manufacturer for evaluation purposes.

9.0 Amazing
  • Exceptionally comfortable
  • Fantastic bass — truly well done
  • Great tonal balance overall and quite detailed/well-layered
  • Solidly wide soundstage
  • Modular cable
  • Much more expensive than the preceding S12 and much of the planar competition
  • Aesthetics won’t be everyone’s cup of tea


Christopher Coke

Chris cut his teeth on MMOs in the late 90s with text-based MUDs. He’s written about video games for many different sites but has made MMORPG his home since 2013. Today, he acts as Hardware and Technology Editor, lead tech reviewer, and continues to love and write about games every chance he gets. Follow him on Twitter: @GameByNight