STAX SRM-270S – a compact gateway to electrostatic listening

The STAX SRM-270S is a newly developed driver unit created for listeners who want to explore electrostatic earspeakers through a compact and practical system. It succeeds the long-running SRM-252S and is supplied with the SR-X1 as part of the SRS-X1000 electrostatic system. Within the STAX range, the SRM-270S serves as an accessible starting point while incorporating circuit and enclosure developments drawn from more recent driver-unit design. Its small footprint makes it suitable for a desktop, bedside table or dedicated personal listening corner, where it can be used for music, films and other private listening sessions without requiring a full-size amplifier installation.

STAX has revised both the internal circuitry and physical construction for the SRM-270S. A 3 mm-thick aluminium front panel is combined with a larger extruded aluminium enclosure, helping the chassis manage operating heat more effectively. The first amplifier stage uses a modern low-noise FET, while the output section features an improved emitter-follower circuit. Its stated frequency response extends from DC to 35,000 Hz at +0/-3 dB, with 58 dB of amplification and harmonic distortion rated at 0.01% or less at 1 kHz and 100 V rms. The unit provides a maximum output voltage of 280 V rms at 1 kHz and a DC 580 V bias supply for compatible electrostatic earspeakers.

A single RCA input allows the STAX SRM-270S to receive a line-level signal from a suitable DAC, streamer, CD player, preamplifier or other source component. The parallel RCA output passes that signal onward, making it easier to add the electrostatic driver unit to an existing hi-fi system without removing another amplifier from the signal path. Measuring 132 mm wide, 38 mm high and 153 mm deep excluding protrusions, and weighing 540 g, it can be repositioned easily when a listening space changes. Keep the ventilation area around the aluminium case clear and use the included AC adaptor to supply the required DC 12 V at 500 mA. For a space-efficient introduction to STAX electrostatic earspeakers, the SRM-270S is a well-considered place to begin.