STAX SR-009D

The STAX SR-009D is an electrostatic headphone that brings back into production one of the most iconic models in the history of the Japanese manufacturer, reviving the design that gave rise to the current flagship models of the SR series. After production ceased following the introduction of a new flagship, the SR-009 returns in an updated version developed in response to the numerous requests from enthusiasts around the world. While preserving the design philosophy that made it legendary, it introduces several refinements that improve usability and long-term practicality.

At the heart of the design is a large circular electrostatic driver engineered to deliver exceptionally accurate and natural sound reproduction. Its core technology is the innovative MLER (Multi-Layer Electrode) system, first introduced with the original SR-009 and later adopted as the foundation for STAX's current high-end models. The fixed electrodes are manufactured by joining three thin stainless steel plates using a sophisticated thermal diffusion bonding process performed under vacuum conditions, creating an atomic-level bond without the use of adhesives. This construction achieves outstanding diaphragm flatness, dramatically reduces resonances, and ensures highly efficient sound wave transmission, resulting in exceptionally transparent, precise, and highly detailed sound reproduction.

The SR-009D also introduces a detachable cable system, now standard across the current STAX lineup. This design simplifies maintenance and cable replacement while allowing users to upgrade to higher-quality cables in the future, enhancing the headphone's versatility over time.

The mechanical design has also been updated with a new injection-molded housing engineered to reduce overall weight without compromising structural rigidity. The headband features a ten-position adjustment mechanism that allows precise fitting to a wide range of head sizes, ensuring stability and long-lasting comfort during extended listening sessions. Compared to the original model, the body finish, cable material, and outer housing have also been updated, preserving the unmistakable identity of the SR series while introducing a more modern and practical design.

From a sonic perspective, the SR-009D retains all the qualities that made the original model a reference in the world of electrostatic headphones. Its presentation is characterized by exceptional transparency, lightning-fast transient response, and an extraordinary ability to reveal even the finest musical details with complete naturalness. The soundstage is expansive, airy, and precisely focused, while the midrange delivers remarkable realism and harmonic richness. Bass is articulate and well-controlled, and the treble extends effortlessly with outstanding precision and refinement. Its tonal neutrality and extremely low coloration allow recordings to be reproduced with exceptional fidelity, making the SR-009D one of the finest expressions of STAX's electrostatic technology.

To fully realize its performance potential, the SR-009D must be paired with a dedicated electrostatic headphone amplifier, such as those in the STAX SRM series, specifically designed to provide the proper drive voltage and allow the headphone to deliver the extraordinary performance that has made it a benchmark in the world of high-end personal audio.

Technical specifications:

• Type: Open-back push-pull electrostatic headphone
• Driver unit: Large circular electrostatic driver
• Frequency response: 5 Hz – 42 kHz
• Electrostatic capacitance: 110 pF
• Impedance: 145 kΩ
• Sensitivity: 101 dB
• Bias voltage: 580 V DC
• Cable conductor: OFC (Oxygen-Free Copper)
• Cable: Low-capacitance parallel 6-conductor cable; 2.5 m length
• Ear pads: Genuine sheepskin leather (skin-contact surface); synthetic leather (outer section)
• Weight: 452 g (headphones only)