Small in size, Ruthless in power. The new Ruthless Audio 400.4 Micro Amplifier is engineered for serious enthusiasts who demand big performance without sacrificing space. Don’t be fooled by its compact footprint—this amp delivers a clean, dynamic 400 watts of RMS power across 4 channels, giving your speakers the clarity, punch, and authority they deserve.  The ultra-Compact Design is perfect for tight installs, motorcycles, powersports, or stealth builds.  The 400.4 is a clean and efficient Class-D design. 

The goal is crystal-clear sound that is meant for minimal distortion.  Our 400.4 can be versatile 4-Channel as you can power your full system or bridge channels for even more output flexibility.  Built Ruthless Tough – High-efficiency circuitry with premium components built to last.  Whether you’re upgrading a factory system or pushing a high-end aftermarket build, the 400.4 Micro Amplifier delivers the muscle and finesse your music deserves, in a package small enough to hide almost anywhere.

RMS POWER: 100W x 4 @ 14.4V - 2 ohms
RMS POWER: 60W x 4 @ 14.4V - 4 ohms
Frequency Response: 20Hz - 8KHz
High Pass Filter: 20Hz - 8kHz
Low Pass Filter: 50Hz - 8kHz
Signal to Noise Ratio: 95dB <
Fuse Rating: 60A
Operating Voltage: 9 to 16 Volts
Length 7.25” overall (heatsink 6.375”)

Width    4.7”

Height   2.2“

Extended Warranty

No – Standard Warranty (1 Year)

Includes the standard 1-year manufacturer defect warranty.

Yes – Extended Warranty (2 Years Total)

Adds 1 additional year of manufacturer defect warranty coverage (2 years total).