STAX SRM-252S Electrostatic Headphone Amplifier, Wired, Silver

STAX SRM-252S Electrostatic Headphone Amplifier, Wired, Silver

Hear Your Music With Electrostatic Clarity—Anywhere a CD Case Fits

Experience the unmistakable Stax electrostatic sound without surrendering your desk space. The SRM-252S is a compact, class‑A, DC‑coupled driver unit that unlocks the speed, transparency, and effortlessness Stax earspeakers are famous for—delivering a wide, grain‑free soundstage and pristine microdetail from a chassis barely larger than a CD case. Its aluminum extrusion body pulls double duty as a heat sink for rock‑solid reliability session after session.

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Why Audiophiles Choose This Product

• • Sound quality: Fast, clean, and “electrostatic effortless.” The SRM-252S reveals nuance with low distortion and excellent treble smoothness—an ideal match for Stax Lambda‑series and other Pro‑bias earspeakers. Community comparisons note it’s a capable, musical entry into electrostatics, with bigger Stax amps adding scale primarily at very high levels.
• • Engineering: Fully discrete, all‑FET, class‑A topology with an emitter‑follower output stage for robust drive and smooth tonality; DC‑coupled signal path with no coupling capacitors.
• • Practicality: Ultra‑compact, cool‑running chassis with front silver panel and black body; parallel RCA “loop‑out” lets you feed a speaker amp or recorder from the same source.
• • Compatibility: Standard Stax 5‑pin PRO output with 580V bias drives all modern Pro‑bias Stax earspeakers; accepts any analog RCA line‑level source.
• • Unique advantage: True Stax house sound from a travel‑friendly form factor—built to integrate seamlessly into existing rigs without consuming a rack shelf.

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What’s Included

• • Main product: STAX SRM‑252S electrostatic driver unit (silver front/black body), Pro‑bias 5‑pin output, RCA input with parallel out.
• • Primary accessory: Region‑appropriate 12V AC adapter (the unit runs on DC 12V, ~4W).
• • Documentation: User manual and warranty information. (Manuals are available from STAX.)

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Technical Specifications

Specification	Value	Notes
Product Type	Wired	Analog RCA input; 5‑pin Stax PRO output; RCA parallel out.
Frequency Response	DC – 35 kHz	Preserves sub‑bass linearity and airy treble extension.
Gain	58 dB	Plenty of headroom with modern DACs and streamers.
Harmonic Distortion	≤0.01% (1 kHz at 100 Vrms)	Clean, low‑grain presentation.
Maximum Output	280 Vrms (1 kHz)	Drives Pro‑bias earspeakers to realistic levels.
Input/Output	RCA x1 with parallel out; Stax PRO 5‑pin	Easy integration with speaker rigs or recorders.
Input Impedance	50 kΩ (RCA)	Friendly to most sources.
Rated Input Level	125 mV for 100 V output	Quiet listening to concert‑level headroom.
Bias Voltage	580 V DC (PRO)	Compatible with all modern Stax earspeakers.
Power	DC 12 V; 4 W	Efficient, class‑A design.
Dimensions	132 x 38 x 132 mm	Desk‑friendly “CD‑jacket” footprint.
Weight	540 g	Solid build; stays put on the desktop.
Finish	Silver front / black body	Clean, modern aesthetic.

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Professional Recognition

• • Reviews: Hi‑Fi+ praised the SRS‑3100 system (SR‑L300 + SRM‑252S) for delivering the “first‑taste” Stax conversion—effortless detail and transparency that recalibrates expectations for headphone sound.
• • Community feedback: Head‑Fi listeners consistently find the SRM‑252S a “perfectly capable little unit” that captures the Stax sound, noting larger amps can add slam and control at higher volumes. Others report the 252S can sound a touch lean versus bigger drivers, especially in the lowest octave—useful context for system matching.
• • Heritage: STAX has handcrafted electrostatic “earspeakers” and driver units in Japan since 1938, pioneering the category and refining it through successive generations.
• • Design insight: Class‑A amplification with emitter‑follower output and an aluminum extrusion chassis acting as a heat sink—trickle‑down engineering from larger SRM models, tailored for a compact footprint.

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Setup and Compatibility Notes

• • Source: Connect any RCA line‑level source (streamer, DAC, preamp, or CD player) to the SRM‑252S; use the parallel RCA out to loop the same signal to a speaker amplifier or recorder.
• • Earspeakers: Drives all Stax “PRO” 5‑pin, 580‑volt‑bias earspeakers (e.g., SR‑L300, SR‑L500 MK2, SR‑L700 MK2, SR‑007, SR‑009/S). Not compatible with dynamic, planar magnetic, IEMs, or older 6‑pin “Normal Bias” Stax models.
• • Placement: Allow ventilation; the class‑A circuit runs warm by design, with the aluminum case dissipating heat for long‑term stability.

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The Bottom Line

The STAX SRM‑252S distills the brand’s electrostatic magic into a compact, reliable driver unit that’s easy to live with and easier to love. If you want authentic Stax transparency and speed in a desktop‑friendly package—with smooth class‑A drive, Pro‑bias compatibility, and smart pass‑through connectivity—the SRM‑252S is the proven, research‑backed entry point that keeps the focus on the music.

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Notes on research and validation:

• Technical specifications verified against multiple sources including Headphone Auditions, Hi‑Fi+, and retailer documentation; finish and body color confirmed by Auditorium. Compatibility and connector type validated via e‑catalog and Stax references; design features cross‑checked with retailer technical notes and Stax materials. Community impressions summarized from Head‑Fi threads to reflect typical listening feedback.