The Stax SRM-400S Headphone Amplifier is a meticulously engineered solid-state “energizer” from Stax, specifically crafted to unleash the full potential of their electrostatic earspeakers. As the successor to the acclaimed SRM-353X, the SRM-400S elevates performance with a pure Class A solid-state DC amplification design, incorporating high-quality non-magnetic FETs for exceptional linearity and detail.

A significant upgrade lies in its newly designed power transformer, featuring independent windings for both low and high-voltage circuits, which dramatically enhances efficiency, reduces noise, and refines the overall sound quality. Housed in a robust, hybrid aluminum chassis, the amplifier effectively suppresses external vibrations and interference. It offers both RCA and XLR (balanced) inputs for versatile connectivity and provides two 5-pin Pro bias (580V DC) outputs, allowing two pairs of Stax headphones to be driven simultaneously. Delivering a wide DC-90kHz frequency response and ultra-low distortion, the SRM-400S offers a transparent, dynamic, and exceptionally clean sound, making it an ideal choice for discerning audiophiles seeking precise control and fidelity for their Stax electrostatic system.

- New semiconductor driver with J-FET in the amplification stage. The custom-made, low-noise dual FET is low-noise.
- The power transistor array with effective heat dissipation through a large-sized heat sink
- Hand selected matching FET
- High-definition film capacitors are used
- Bypass volume control switch
- Volume control is EMI shielded
- Switchable RCA and XLR inputs. RCA parallel out.
- The newly developed large-sized aluminum insulator combined with new vibration-proof material and high frictional coefficient (grip power) have been employed.

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
Dimension: 240W x 103 H x 393 D mm (maximum protruding portion included)
Weight: 6.3kg

Orders ship Sunday through Friday from our offices in Dubai, UAE.

In-stock products typically ship within 48 hours and should be expected to arrive in 3-4 business days. Orders outside of the UAE should be expected to arrive in 5-7 business days.

Pre-order and backorder products will state the approximate delivery timeline beside the Add To Cart button.

If you would like to place a custom order, chat with our specialists for a guided shopping experience. Once your order has been placed, a timeline will be provided depending on your order details.

- Free delivery within the UAE
- Shipping charges will be calculated upon checkout for orders outside of the UAE (Bahrain, Oman, Kuwait, Saudi Arabia & Qatar).
- Taxes and duties are calculated according to the applicable laws of the state or country an item is shipped to and are the customer's responsibility.

For additional information on shipping and our exchange & return policy visit our help center.

Installation charges are applicable and can be paid upon delivery for our clients based in Dubai.

- Installation Charges: AED 450 Per Hour
- Speaker Cables: AED 32 Per Meter
- Trunking: AED 10 Per Meter

For clients based outside of the UAE, please contact our specialists and we will share an estimate based on your requirements.