Stax Ltd. is a Japanese audio company founded in 1938 and headquartered in Saitama, specializing in high-end electrostatic headphones — which the company insists on calling "earspeakers" to distinguish them from conventional dynamic designs. In 1960, Stax released the SR-1, widely regarded as the world's first commercial electrostatic headphone, and the company has built its reputation almost entirely around refining that technology. Because electrostatic transducers require a high bias voltage rather than a standard amplifier output, Stax also designs the dedicated tube and solid-state "driver units" needed to power their headphones, sold as matched systems.

The lineup is anchored by two long-running families: the rectangular Lambda series (including the SR-L300, SR-L500, and SR-L700) and the flagship Omega series, represented by the SR-007, the SR-009/SR-009S, and the SR-X9000. Driver units such as the SRM-T8000 and SRM-D50 round out the catalog, and the company uses a proprietary five- and six-pin Pro Bias connector that ties customers into the Stax ecosystem. The brand was acquired by Chinese audio manufacturer Edifier in 2011, which has continued the Saitama-based engineering operation.

Stax has a niche but devoted following in the audiophile and mastering communities, valued for the low mass and fast transient response of its electrostatic drivers. The earspeakers are commonly used as critical-listening references rather than tracking or stage tools, and the brand is frequently cross-shopped against other top-tier headphone makers like HiFiMan and Sennheiser's HE-series.

Stax has 3 products cataloged on Equipboard, including Headphones & In-Ear Monitors, Reverb Effects Pedals, and Fuzz Effects Pedals.