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Stax Srx MK3 Pro Headphones With Srm-1/Mk-2 Amplifier Tested Sounding Perfect, Probably the best headphones we ever tested. They are close to brand new.The Stax SR-X MK3 headphones are vintage electrostatic "earspeakers" known for smooth, natural sound, requiring a dedicated Stax energizer (like the SRD-7) for their ~230V bias, featuring 1.5-micron diaphragms, a wide frequency response (e.g., 20-70kHz), and operating on a unique electrostatic principle, not typical wired specs. Key is the bias voltage (Normal or Pro) and their need for an energizer, not standard headphone jacks. Key Specifications (Varies slightly by variant, especially Normal vs. Pro bias):Type: Electrostatic Earspeaker (Open-Back, Over-Ear).Sound Principle: Electrostatic (Requires Stax Energizer/Amp).Diaphragm: ~1.5 micron (same as Gamma/Alpha Pro).Frequency Response: Often cited around 20 Hz - 70 kHz (tolerance unstated).Sensitivity: ~97 dB SPL @ 100V RMS (with 230V bias).Max Output: ~110 dB SPL (with 230V bias).Bias Voltage: Normal Bias (e.g., 230V) or Pro Bias (580V).Weight: Around 290g (without cord).Connection: Proprietary Stax 5-pin connector (to energizer).
The Stax SRX MK3 Pro electrostatic headphones with SRM-1/MK2 amp originally retailed new for around USD4,000 back in their heyday, making any used set a steal by comparison. At USD850, this listing sits squarely in the bargain zone against our database of 28 recent comparables, where the median asking price is USD1,740 (25th percentile USD834, 75th USD2,419). It's a solid entry-level deal for these ultra-rare '80s panels, assuming good condition.
Buyers should verify the condition of the EHT panels—no cracks, haze, or dust specks that could kill dynamics—and test for the amp's full output with a known Stax driver unit. Confirm both original power cords and any stock cables are included, as replacements are pricey and scarce. Unknown condition raises red flags; demand detailed photos and seller history.
Independent perspective — not a price guarantee. Always verify condition, accessories and provenance before purchase.
Stax traces its origins to 1938 in Tokyo, Japan, when Naotake Hayashi founded Showa Kouon Co., Ltd. in Chiyoda-ku. Initially focused on wax disc recording, metal master production, and audio equipment for film soundtracks, the company evolved through the postwar era. In 1950, it launched its first high-frequency condenser microphone, adopted by NHK, and renamed itself STAX Co., Ltd. in 1963, honoring its pioneering Stax-1 mic. A brief suspension in 1995 due to economic pressures gave way to revival, preserving its legacy under family leadership.
The brand specializes in electrostatic headphones, known as "EARSPEAKERS," debuting with the world-first SR-1 in 1960. This innovation spawned enduring lines like the SR series, produced for decades with incremental refinements for superior resolution and staging. Stax complements these with dedicated electrostatic amplifiers and select accessories, eschewing conventional speakers, turntables, DACs, or cables to hone its transducer expertise.
Stax commands a niche high-end position among audiophiles and professionals, revered for unmatched transparency and fidelity that rivals cost-no-object loudspeakers. Its 85-year heritage cements it as a boutique icon in electrostatic technology, far from mass-market fare, appealing to discerning buyers seeking pinnacle sonic transduction.
See all Stax listings on RADAR.
