Small in size. Ruthless in power. The Ruthless Audio 400.4 Micro packs 400 watts of total RMS output into an ultra-compact 4-channel chassis only 7.25 inches long. It is made for tight installs, stealth OEM upgrades, motorcycles, powersports builds, and custom systems where amplifier space is limited but sound quality and real power still matter.WHY CHOOSE THE RUTHLESS AUDIO 400.4 MICRO? 100W × 4 @ 2Ω (14.4V) — real usable power for upgraded component and coaxial speakers. 60W × 4 @ 4Ω — a clean match for many daily-driver full-range systems. 1-Year 2Ω Warranty Coverage — standard manufacturer defect coverage includes operation down to 2 ohms per channel when warranty conditions are met. Ultra-Compact 7.25 in. Chassis — fits under seats, behind panels, and in tight custom locations where a full-size amplifier will not. High-Efficiency Class-D Design — strong power density with low heat for its size. Bridgeable 4-Channel Layout — channels can be paired for higher-output 2-channel applications when wired to the proper bridged impedance. Onboard HPF & LPF — wide crossover ranges let you tune the amplifier for mids, highs, or bridged applications. 95dB Signal-to-Noise Ratio — designed for clean full-range playback without excessive background noise. FULL SPECIFICATIONS RMS Power @ 2Ω (14.4V) 100W × 4 RMS Power @ 4Ω (14.4V) 60W × 4 Total RMS Power 400W Standard Warranty Load Down to 2Ω per channel when warranty conditions are met Amplifier Class Class-D Channels 4 (bridgeable to 2) Frequency Response 20Hz–8kHz High-Pass Filter 20Hz–8kHz Low-Pass Filter 50Hz–8kHz Signal-to-Noise Ratio 95dB Fuse Rating 60A Operating Voltage 9–16V Overall Length 7.25 in. Heatsink Length 6.375 in. Width 4.7 in. Height 2.2 in. AMPLIFIER & WIRING RECOMMENDATIONSUse quality OFC power and ground wiring with proper fusing and a short, low-resistance ground. A 4 AWG power/ground kit is a strong choice for installations where the run length and system layout justify it. Route RCA/signal cables away from power wiring to reduce noise.For bridged operation, use a minimum 4-ohm bridged load. Standard warranty coverage is down to 2 ohms per channel in stereo operation.For motorcycle and powersports installs, mount the amplifier securely, isolate it from excessive vibration, and protect it from direct moisture. Operation below 11V and excessive clipping are not covered under warranty.FREQUENTLY ASKED QUESTIONSIs the 400.4 Micro warrantied at 2 ohms per channel?Yes. The standard 1-year manufacturer defect warranty covers operation down to 2 ohms per channel when Ruthless warranty requirements are met.Can I bridge the 400.4 Micro?Yes. Channels can be bridged in pairs for a 2-channel configuration. Keep the bridged load at 4 ohms or higher.Is it a good choice for a motorcycle or powersports build?Yes, especially where space is limited. The 7.25-inch overall length makes it easy to package, but it should still be protected from water and excessive vibration.What wiring should I use?Use quality OFC wiring sized for the installation and 60A fuse requirement. A properly installed 4 AWG kit provides comfortable current capacity for many builds.What can void warranty coverage?Warranty does not cover vibration damage, wire or debris inside the amplifier, wiring below the covered impedance, external RCA damage, excessive clipping, or operation below 11V. Full warranty terms apply.EXTENDED WARRANTYNo – Standard Warranty (1 Year)Includes the standard 1-year manufacturer defect warranty, including covered operation down to 2 ohms per channel when all warranty requirements are met.Yes – Extended Warranty (2 Years Total)Adds 1 additional year of manufacturer defect warranty coverage for 2 years total.
