SRM-700S Electrostatic Headphone Driver Unit (Color Black)

Pure solid-state control. Uncompromising musical detail The SRM-700S is a fully discrete, all-solid-state electrostatic driver designed for exceptional speed, authority and resolution. Its custom low-noise dual-FET input stage, J-FET amplification and large-current emitter-follower circuit are engineered to bring out the full potential of STAX PRO-bias earspeakers. With up to 450 Vrms of output capability, the SRM-700S delivers confident control across demanding passages while preserving the smallest details in a recording. A carefully matched FET design, high-definition film capacitors and a power-transistor array with a substantial heatsink support stable, low-noise performance. Balanced XLR and RCA inputs make system integration straightforward, while the volume-bypass function and RCA parallel output offer added flexibility for more advanced setups. Choose the SRM-700S for a fast, clean and highly precise presentation that lets complex recordings remain composed, articulate and deeply revealing. Key highlights Fully discrete all-FET DC amplification design J-FET amplification and large-current emitter-follower output circuit Up to 450 Vrms maximum output Fast, controlled and highly detailed sound Switchable RCA and balanced XLR inputs Volume-bypass function and RCA parallel output Designed for STAX PRO-bias (580 V) earspeakers Specifications Type: All-stage FET configuration DC amplification driver unit Frequency response: DC - 100kHz (with one SR-009S) Gain: 60dB Harmonic distortion: 0.01% or less (1kHz/100Vrms output) Input impedance: 50kΩ (RCA), 50kΩx 2 (XLR) Maximum output voltage: 450Vrms (1kHz) Bias voltage: PRO 580V Operating temperature / humidity: 0 to 35 degrees C / less than 90% (non condensing) Input terminal: RCA x 1, XLR x 1 Output: RCA parallel output terminal Power consumption: 46W Dimensions: 240W x 103H x 393D mm (maximum protruding portion included) Weight: 6.3kg Gramophone Dreams #102: Stax SR-007S Earspeakers "Stax's SRM-700S driver unit is all JFET, and it is so transparent I swear that in the quiet passages I could hear its JFETs flowing current. Which suggests the 700S is a simple, naturally clean design with minimal feedback. Listening to Serge Gainsbourg's Histoire de Melody Nelson, my attention kept focusing on how Serge and Jane Birkin pronounced their words. With the 700S powering the 007S, each word had its own shape and internal structure.” - Herb Reichert