The SRM-252S is an exclusive driver unit (amplifier) for driving STAX ear speakers with PRO-bias 5 pins. Its line input can directly connect to the audio output terminal of CD player, portable audio player and PC. The SRM-252S has a simple design that excels in sound quality employing the carefully selected newest high-voltage transistors and low-noise FETs. The output stage featuring the emitter-follower configuration reinforces the driving performance and also realized the smooth sound quality. Moreover, the class-A amplification throughout the stages with no coupling capacitors reproduces exhaustively the finest nuance of music. Although the SRM-252S includes a class-A DC amplifier in a compact CD jacket size case, the internal heat is effectively dissipated through the chassis of aluminum extrusion material to improve the reliability over a long period of time. Also, the parallel output terminal was added to distribute the source signal so that a loud speaker may also be simultaneously used when source equipment has only a pair of output terminals.

Specifications: SRM-252S Driver unit 
●Frequency response:    DC- 35 kHz (40Vr.m.s. output SR-207, when using one unit)
●Rated input level:    125 mV with 100V output
●Maximum input level    30 V r.m.s. with volume at minimum setting
●Amplification:    58 dB (x800)
●Total harmonic distortion    max. 0.01% (1 kHz / during 100 V r.m.s. output) 
●Input impedance    50 kΩ (RCA) 
●Maximum output voltage:    280 V r.m.s. / 1 kHz 
●Standard bias voltage    DC580 V (PRO bias)
●Power consumption    DC12V, 4W/ Exclusive AC adaptor attached For your area
●Temperature range for use    Between 0º and 35ºC, max. 90% (no condensation)
●External dimensions    132 (W) × 38 (H) × 132 (D) mm (without Knob, Pin jack)
●Weight    540g