Stax SRM-400S: PRO class headphone amplifier

Owners of Stax PRO electrostatic headphones will be able to enhance their sound with the new SRM-400S Transistor Power Amplifier.

It replaced the SRM-353X and, according to the manufacturer, has many advantages. The new product produces a nominal bias voltage of 580 V and amplifies the audio signal with a distortion of no more than 0.01%.

The device is assembled in the circuitry of a DC amplifier, in all stages of which, as in the older model SRM-700S, field-effect transistors operate. A custom low-noise double field-effect transistor STAX is installed at the input. These parts are said to have been selected as carefully for the SRM-400S as they were for the SRM-700S.

In the low voltage circuit, the SRM-400S has a newly developed power transformer, which increases the accuracy and reduces the power consumption of the new product. At the same time, the design of the chassis was also changed, which became stiffer due to the use of massive aluminum parts – this is intended to reduce the vibration effects on the signal.

The Stax SRM-400S headphone amplifier will appear in May 2021. In the US, it will cost about $2,100.