Overview

The LETSHUOER S15 is a third-generation planar-magnetic in-ear monitor using a 14.8 mm planar driver plus a 6 mm R-Sonic passive filtering module. The shell combines an aluminum-magnesium faceplate with a 3D-printed resin body, and the stock cable includes 2.5/3.5/4.4 mm swappable plugs. Reference price is 330 USD.

Scientific Validity

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• What’s measured: Independent frequency-response (IEC-711–type) data are available and show a warm, relaxed tuning versus neutral targets. Manufacturer specs: 30 Ω, 106 dB. [1][2][3]
• What isn’t: We could not locate credible third-party THD datasets for S15. Claims of “high resolution” therefore remain subjective.
  Verdict: Some FR coverage exists, but the evidence is insufficient to claim strong scientific transparency beyond a mid score.

Technology Level

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• 14.8 mm planar with dual-chamber structure and a 6 mm R-Sonic passive module shaping pressure/bass behavior. [1]
• HeyGears 3D-printed shell; modular cable with 2.5/3.5/4.4 mm plugs included. [1][2]
  Incremental, well-executed engineering rather than a breakthrough.

Cost-Performance

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Baseline: S15 at 330 USD. [1]
Cheapest equal-or-better alternative (measured): Etymotic ER2SE — well-documented 35–42 dB isolation and flat/DF-aligned FR, widely sold at 99.95 USD. [4][5]

• Why it qualifies: ER2SE’s target adherence and isolation are objectively stronger than S15’s third-party FR shows; both are measurable performance axes. [3][4]
• CP result: 99.95 ÷ 330 = 0.30 → 0.3.
  Note: If you specifically want planar dynamics and a thinner profile, 7Hz Timeless II is 229 USD and commonly quoted THD < 0.2% @ 1 kHz, still under S15’s price but not as neutrally measured as ER2SE. [6]

Reliability & Support

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Warranty: 1-year on IEMs / 3-month on cable from LETSHUOER; typical for the segment. [7] Documentation and contact channels are adequate.

Rationality of Design Philosophy

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Coherent goal of easy-listening warmth, comfort, and rich accessories. It doesn’t prioritize strict neutrality/measurement-first design, so we keep this at 0.4.

Advice

Buy if you want a premium-feeling planar set with modular plugs and relaxed tuning.
Skip if you prioritize measured neutrality/value—ER2SE (and similar well-measured dynamics) are objectively better buys.

References

[1] LETSHUOER — S15 Product Page: https://letshuoer.net/products/letshuoer-s15-third-generation-14-8mm-planar-driver-r-sonic-passive-filtering-module-hifi-wired-in-ear-monitor
[2] LETSHUOER — S15 Release / HeyGears collaboration: https://letshuoer.net/blogs/news/letshuoer-s15-release
[3] Headphones.com — “Letshuoer S15 Review: Not At This Price” (FR & analysis): https://headphones.com/blogs/reviews/letshuoer-s15-review-not-at-this-price
[4] Etymotic — ER2SE official page (35–42 dB isolation, flat response): https://etymotic.com/product/er2se-earphones/
[5] Audio46 — ER2SE retail price (USD 99.95): https://audio46.com/products/etymotic-er2-noise-isolating-earphones
[6] Linsoul — 7Hz Timeless II (USD 229, THD < 0.2% @1 kHz): https://www.linsoul.com/products/7hz-timeless-ii
[7] LETSHUOER — Warranty Policy (1-year IEMs / 3-month cable): https://letshuoer.net/pages/warranty-policy

(2025.9.2)