Headphones — Stax SR-009D

The SR-009D is a flagship electrostatic headphone from Stax, built with an exceptionally wide bandwidth and an extraordinarily high impedance characteristic of electrostatic driver technology. The SR-009D brings Stax's most accomplished current engineering to an open-back electrostatic format.

Key specs that matter

The transducer uses electrostatic or planar-magnetic driver technology in an open-back, over-ear, wired configuration. Frequency response spans an exceptionally wide 5Hz to 42,000Hz within plus-or-minus 10dB. Sensitivity is 101dB SPL at 1kHz/1mW, with an extraordinary impedance of 145,000 ohms at 1kHz - a characteristic figure for electrostatic headphone technology, which requires a dedicated electrostatic amplifier rather than a conventional headphone amp. Weight is 452g.

Sound and use context

Expect the exceptionally detailed, precisely engineered character Stax's legendary electrostatic driver technology is broadly celebrated for, with the exceptionally wide 5Hz-42kHz bandwidth reflecting Stax's flagship-tier current engineering ambition.

Pairing

The extraordinary 145,000-ohm impedance requires a dedicated Stax electrostatic amplifier, such as the SRM-700S or SRM-700T, using the brand's proprietary Pro-bias connection - conventional headphone amplifiers cannot drive this headphone.

Alternatives

Stax's own SR-X9000 offers a related flagship electrostatic alternative within the same broader catalogue.