Overview

The RS Five Clear is a single-dynamic “listening monitor” IEM featuring a 9.2 mm Myrinx EL-B driver in a clear medical-grade resin shell with a stainless nozzle and an aluminum faceplate. It uses a Long-Type Pentaconn Ear connector emphasizing robustness and moisture resistance[1]. Typical US street price is around 349.99 USD[2].

Scientific Validity

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Published specs list 20–40,000 Hz bandwidth, about 110 dB sensitivity and 32 Ω impedance (manufacturer/retailer-published values)[2][3]. These are reasonable on paper, but there are no independent lab measurements (FR/THD/isolation) yet. Extension to 40 kHz is outside human hearing; pending third-party data we keep the neutral 0.5.

Technology Level

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Material and mechanical choices are thoughtful: a thin beryllium-alloy dome driver, precision medical-grade resin shell, stainless nozzle, and Long-Type Pentaconn Ear for better contact stability and moisture mitigation[1]. Competent and evolutionary rather than groundbreaking.

Cost-Performance

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Comparator (equal-or-better): Etymotic ER2XR, which has extensive third-party measurements and strong passive isolation[5][6]. US pricing we could confirm is 149.99 USD from the manufacturer store[8], while RS Five Clear sits at 349.99 USD[2].
Calculation: 149.99 ÷ 349.99 = 0.428… ⇒ 0.4 (one-decimal rounding).
A cheaper, well-measured alternative exists; therefore, value is weak.

Reliability & Support

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The official page lists 1-year warranty for the earphones and 90 days for the cable/accessories[1]. The Long-Type Pentaconn Ear connector is a sensible choice for durability and contact reliability[1]. Long-term field reliability stats are not yet available.

Rationality of Design Philosophy

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Assessed independently of scientific validity: moisture-resistant Long-Type connectors, medical-grade shell for manufacturing consistency and fit, and a practical accessory set show alignment between purpose and means[1]. The clear shell is mostly aesthetic and 40 kHz bandwidth adds little audible value, so overall we rate the design moderately rational.

Advice

If you prioritize verified performance, start with the Etymotic ER2XR[5][6]. The RS Five Clear suits users valuing fit/finish, connector durability, and a clear-shell aesthetic with clear domestic warranty terms. Independent measurements would clarify its standing further.

References

[1] Acoustune — RS FIVE product page (structure, warranty, accessories)
https://www.acoustune.jp/rs-five

[2] AccessoryJack — RS FIVE product page (USD price, specs)
https://www.accessoryjack.com/products/acoustune-rs-five-dynamic-driver-in-ear-monitor-iem-earphone-with-pentaconn-ear-connector-3-5mm-cable

[3] HKTVmall — ACOUSTUNE RS FIVE (20–40,000 Hz / 110 dB / 32 Ω listing)
https://www.hktvmall.com/hktv/en/main/Chill-Point/s/B0480001/Gadgets-%26-Electronics/Gadgets-%26-Electronics/Headphone-%26-Earphone/Wired-Earphone/ACOUSTUNE-RS-FIVE-InEar-Monitor-Wired-Earphones/p/B0480001_S_ACOUSTUNE_RS5

[4] Kakaku — RS FIVE CLEAR ACO-RS-FIVE-CLR (Japan street price)
https://kakaku.com/item/K0001698754/

[5] Audio Science Review — Etymotic ER2XR Review (IEM) (independent measurements)
https://www.audiosciencereview.com/forum/index.php?threads/etymotic-er2xr-review-iem.29818/

[6] Etymotic — ER2XR product page (specs, isolation description)
https://etymotic.com/product/er2xr-earphones/

[7] Yodobashi — ER2XR Japan street price
https://www.yodobashi.com/product/100000001004327466/

[8] Etymotic — Shop listing showing 149.99 USD for ER2XR (often discounted)
https://etymotic.com/shop/?product-page=5

(2025.8.16)