STAX SRM-353X

The SRM-353X is a specific headphone amplifier (driver), designed especially to optimally power STAX electrostatic headphones. Strictly selected, audiophile-grade audio components improve the sound signature, and a new detailed circuit design study has further extended the bandwidth. XLR input terminals allow connection to the balanced inputs of audio devices to benefit from their superior performance.

The first stage features dual low-noise FET (field effect) transistors, and an all-stage direct-coupled DC class A configuration without capacitor coupling, resulting in a natural sound signature with rich detail. The use of an improved emitter-follower circuit for the output stage enables a wider bandwidth sound reproduction, allowing for more extended high-frequency dynamics and enhanced sound quality. An XLR balanced input is provided in addition to the RCA input jacks, allowing connection to a wider range of audio devices. The driver features a custom-designed coaxial volume control. It features the superb usual STAX housing made of non-magnetic aluminum alloy. Low-aging components have been custom selected for their characteristics and performance in terms of sound signature.

• Class A output stage with DC coupling and no negative feedback
• Volume/balance control via 4-way potentiometer

Measurements

• Frequency response: DC to 90 kHz (with SR-L series headphones)
• Maximum input level: 100mV (for 100V output)
• Gain: 60dB
• Maximum total harmonic distortion: < 0.01% (with SR-L500, for 100 mVrms, at 1 kHz output)
• Input impedance: 50 kOhms (RCA)
• Maximum output voltage: 400 V RMS / 1 kHz
• Bias voltage: DC580 V

Connectivity

• 1 switchable input on the connection panel
• Optionally balanced (3-pin XLR connectors) or unbalanced (RCA/phono jacks)
• 1 unbalanced output (RCA/phono jacks)
• 2 headphone outputs

General

• Power supply: AC120V-240V
• Power consumption: 30 W
• Brushed silver aluminum front panel / dark gray body
• Dimensions W x H x D: 150 x 100 x 330mm
• Weight: 2.9 kg