STAX SRM-500T Electrostatic Headphone Amplifier, Wired, Silver

STAX SRM-500T Electrostatic Headphone Amplifier (Wired, Silver)

Hear electrostatic speed with tube warmth—effortlessly.

The SRM-500T brings the legendary Stax “earspeaker” sound to life with a hybrid circuit that blends the ultra-fast clarity of FET input stages with the saturated tone and dimensionality of twin 6FQ7/6CG7 vacuum tubes. A newly designed power transformer lowers noise and boosts efficiency, while a rigid, non‑magnetic aluminum hybrid chassis keeps microdetail intact. The result: a blacker background, more natural body in the mids, and that unmistakable Stax transparency—without fatigue. Available in a refined Silver finish.

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Why Audiophiles Choose This Product

• Primary Benefit: Effortless, transparent sound with just‑right tube warmth. Reviewers consistently note the SRM‑500T’s clear, highly resolving presentation that adds body and ease rather than smearing detail—an inviting listen for hours.
• Technical Benefit: Proven Stax hybrid topology—custom low‑noise dual FET input driving 6FQ7/6CG7 tube output—executed as a fully DC‑coupled amplifier (no coupling capacitors) for purity from source to ‘speakers.
• Practical Benefit: Dual Stax PRO 5‑pin outputs up front, plus rear RCA and balanced XLR inputs (selectable). A parallel RCA “pass‑through” lets you feed another amp or recorder—ideal for flexible systems.
• Compatibility Benefit: Purpose‑built for electrostatic headphones using the Stax PRO standard (580 V bias). It won’t drive dynamic or planar headphones—this specialization ensures optimal performance with Stax earspeakers, especially the Advanced Lambda series.
• Unique Benefit: Stax’s custom dual‑axis, 4‑gang volume control allows precise left/right balance without external balance knobs—subtle but meaningful for reference listening.

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What’s Included

• Main Product: STAX SRM‑500T Electrostatic Headphone Amplifier (Silver) — hybrid FET input + 6FQ7/6CG7 tube output, PRO bias 580 V.
• Primary Accessory: AC power cord; stereo RCA interconnect cable for single‑ended sources.
• Secondary Items: None (electrostatic headphones and XLR cable sold separately).
• Documentation: User manual and warranty.

Note: The SRM‑500T is also produced in Black; this listing is the Silver finish. Availability varies by region.

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Technical Specifications

Specification	Value	Notes
Product Type	Wired	Analog line‑level inputs; Stax PRO 5‑pin headphone outputs
Amplifier Topology	FET input + vacuum‑tube output (6FQ7/6CG7)	Hybrid DC‑coupled design—no coupling caps in signal path
Frequency Response	DC – 90 kHz (with one SR‑L500 MK2)	Wideband response preserves air and microdetail
Gain	60 dB	Plays confidently from typical DAC line levels
Harmonic Distortion	≤ 0.01% (1 kHz / 100 Vrms)	Low THD for clean, unstrained dynamics
Maximum Output Voltage	300 Vrms (1 kHz)	Drives PRO‑bias electrostatics with ease
Bias Voltage	580 V (PRO)	Stax PRO standard; not for “Normal” bias or dynamic cans
Inputs	1 × RCA, 1 × XLR (mutually exclusive)	Rear selector; do not connect both simultaneously
Outputs	2 × Stax PRO 5‑pin (front), 1 × RCA parallel out (rear)	Pass‑through for daisy‑chaining/recording
Power Consumption	38 W	Efficient, newly designed transformer
Dimensions	195 × 102 × 376 mm (W × H × D)	Including protrusions
Weight	3400 g	Solid, resonance‑controlled chassis

Specifications per official Stax sources.

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Professional Recognition

• Awards/Measurements: In AUDIO TEST 05/2021, the SRM‑500T earned an “ausgezeichnet” (excellent) rating of 93% when evaluated with the SR‑L500 MK2, citing ultra‑low distortion, wide bandwidth, and thoughtful usability touches like the dual‑axis volume control.
• Reviews: AudioKey Reviews recommends the SRM‑500T as the sweet‑spot entry into electrostatic amplification, praising its musical warmth and transparency without sacrificing detail.
• Community Feedback: Head‑Fi users report the SRM‑500T as a worthwhile step up from earlier Stax tube units, with a comfortable, easy‑listening balance that pairs especially well with Lambda‑series earspeakers.
• Heritage: Since 1938, Stax has defined the electrostatic category and introduced the world’s first electrostatic headphone in 1960—a pedigree that informs the SRM‑500T’s design DNA.
• Innovation Highlights: Custom low‑noise dual‑FET input stage; new multi‑winding power transformer for higher efficiency and lower noise; hybrid, non‑magnetic chassis; DC‑coupled signal path; custom 4‑gang, dual‑axis volume control.

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The Bottom Line

If you’re ready to experience why electrostatics are synonymous with speed, space, and goosebump detail—but you also crave color and weight—the SRM‑500T is the Stax driver that bridges both worlds. With verified wideband performance, smart connectivity, and the reliability of a modern Stax tube hybrid, it’s a confident, future‑proof foundation for any PRO‑bias earspeaker system. Add your favorite DAC, plug in your Stax, and hear your library open up.

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Setup and compatibility quick notes (for amplifiers/DACs)

• Inputs/Outputs: Use either XLR or RCA input (not both); select the active input with the rear toggle. The RCA parallel out passes the input signal to another device.
• Power/Impedance: Electrostatic systems don’t use traditional headphone impedance specs—drive is defined by voltage. The SRM‑500T delivers up to 300 Vrms with a 580 V PRO bias.
• Headphone support: For Stax PRO 5‑pin electrostatic headphones only (e.g., Advanced Lambda series). Not compatible with dynamic or planar headphones.

Want concise pairing advice for your source and Stax earspeakers? Tell me your DAC and headphones and I’ll tailor a setup.