ESX SX-TWO

With the new SIGNUM SX Mini Series, ESX is expanding its amplifier lineup to include exceptionally compact Class-D power amplifiers that deliver high output power despite their very small dimensions. The SX-TWO combines modern Class-D technology with high efficiency, low heat generation, and an extremely space-saving design.

With an output of 2 x 140 watts RMS at 4 ohms or 2 x 250 watts RMS at 2 ohms, the ESX SX-TWO offers more than enough power reserves for high-quality, high-output front-end systems. In bridged mode, it even delivers 500 watts RMS at 4 ohms, making the amplifier suitable for driving a subwoofer as well. 

Thanks to its compact design, the SX-TWO can be easily installed even in tight spaces—for example, under a seat, behind trim panels, or in the trunk. The die-cast aluminum heat sink ensures effective heat dissipation.

In addition to RCA inputs, the SX-TWO features high-level inputs with the EPS® Error Protection System, making it suitable for integration into many modern factory sound systems. The automatic power-on function can be activated via the input signal or DC detection. In addition, the amplifier is compatible with vehicles equipped with a start-stop system. 

A compact bass-level remote control is also included, allowing for convenient volume adjustment from the driver's seat.

Technical Specifications

• 2-Channel Mini Class-D Digital Amplifier
• SIGNUM SX Mini Series
• Output power at 4 ohms: 2 x 140 watts RMS
• Output power at 2 ohms: 2 x 250 watts RMS
• Bridge power at 4 ohms: 1 x 500 watts RMS
• 2-ohm stable in stereo mode
• 4-ohm stable in bridge mode
• Efficiency: up to 88%
• Total harmonic distortion (THD) according to the manufacturer: 0.003%
• High-pass filter (HPF): 50–500 Hz
• Low-pass filter (LPF): 50–500 Hz
• RCA/Low-Level Inputs
• High-Level Inputs
• EPS® Error Protection System for OEM Radios and Diagnostic Systems
• Automatic Power-On Function / Auto Turn-On
• Signal and DC detection for automatic power-on
• Start-stop capable
• Die-Cast Aluminum Heat Sink
• Compact bass level remote control included
• Compact design for concealed installations
• Dimensions according to the manufacturer: 83 x 38 x 153 mm
  
  

Additional Measurement Results from the CAR&HIFI Test

In the CAR&HIFI test 4/2026, the SX-TWO was also evaluated on the test bench. The actual measured power output was even slightly higher than the manufacturer's specifications.

• Measured channel power at 4 ohms: 2 x 147 watts
• Measured channel power at 2 ohms: 2 x 254 watts
• Measured bridge power: 508 watts
• Measured total power: 514 watts
• Input sensitivity: 190 mV to 5.9 V
• THD+N at 5 watts: 0.005%
• THD+N at half power: 0.022%
• Signal-to-noise ratio: 93 dB(A)
• Damping factor at 20 Hz: 86
• Damping factor at 80 Hz: 89
• Damping factor at 400 Hz: 86
• Damping factor at 1 kHz: 81
• Start-stop function until the vehicle's voltage drops to approximately 7.1 V
• Dimensions measured during testing, including connectors and mounting hardware: 160 x 83 x 39 mm

The test thus confirms, in particular, the SX-TWO's high power density: approximately 150 watts per channel at 4 ohms and more than 250 watts per channel at 2 ohms, while maintaining very low distortion levels