Ruthless Audio
Ruthless Audio 400.4 Micro
Ruthless Audio 400.4 Micro
MICRO 4-CHANNEL • RATED AT 14.4V
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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 RECOMMENDATIONS
Use 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 QUESTIONS
Is 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 WARRANTY
No – 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.
SMALL IN SIZE. RUTHLESS IN POWER.
A REAL FOUR-CHANNEL AMP YOU CAN HIDE.
The Ruthless 400.4 Micro is designed for factory-system upgrades, motorcycles, powersports, stealth builds and any install where space is limited. It is rated at 100 watts RMS × 4 at 2 ohms and 60 watts RMS × 4 at 4 ohms at 14.4 volts.
The compact Class-D platform covers 20Hz–8kHz, uses a 20Hz–8kHz high-pass filter and a 50Hz–8kHz low-pass filter, operates from 9–16 volts and carries a 60-amp fuse rating. The goal is straightforward: useful full-range power without giving up half the install space to the amplifier.
WHY THIS AMP?
THE REASON IT EXISTS.
Clean four-channel output for compact aftermarket and factory-upgrade systems.
A practical match for conventional four-ohm components and coaxials.
Published operating voltage supports conventional vehicle electrical systems.
Overall dimensions are just 7.25 × 4.7 × 2.2 inches.
VERIFIED SPECIFICATIONS
THE NUMBERS.
60A FUSE. SIMPLE, CLEAN INSTALL.
GIVE THE MICRO A SOLID FOUNDATION.
The 400.4 Micro uses a 60-amp fuse and operates from 9–16 volts. Proper wire size, a short clean ground and secure signal connections are usually more important here than overbuilding the electrical system.
Compact does not excuse sloppy wiring. Good voltage and low resistance keep the amp cool, stable and consistent.
SHOP POWER + GROUND →WARRANTY OPTIONS
STANDARD OR EXTENDED.
The standard product option includes a 1-year manufacturer defect warranty. Where offered on the product, the extended-warranty option adds one additional year for 2 years total coverage. Any special low-impedance warranty requirement shown above still depends on the installation meeting Ruthless requirements.
FINISH THE SYSTEM
MATCH THE REST OF THE BUILD.
Choose the speaker or subwoofer load, electrical support, wire size, fuse protection and signal chain before the install starts. The amplifier performs best when the entire system is designed as one package.