MOON 400M Power Amplifier

MOON 400M Power Amplifier

The MOON 400M Monoblock Power Amplifier is the gateway into serious monoblock performance—built to grip demanding loudspeakers with effortless authority while preserving the finesse, texture, and low-level detail that makes high-end listening feel live. Its fully balanced differential topology and oversized toroidal-based power supply deliver fast transients, punchy low-end impact, and a wide-open top end that stays smooth even at higher listening levels. With Class A output to 10 watts and a refined A/AB operating mode, the 400M blends delicacy at low volume with commanding headroom when the music swells. For modern systems and custom installs, it also includes 12V trigger in/out and an RS-232 port for integration and control. The Moon 400M is part of ListenUp's Moon Power Amplifier Collection.

What It's Good At:

• Driving tough speakers with ease thanks to high power and a high damping factor for tight control and dynamics
• Delivering “live-concert” impact with authoritative bass weight and slam without sounding thick or slow
• Revealing fine detail and space with balanced differential circuitry and wide bandwidth performance
• Staying refined at real-world volumes with Class A output (first 10W) and low distortion behavior
• System-building flexibility as a monoblock platform that scales beautifully in high-end stereo setups
• Clean custom-install integration via RS-232 and 12V trigger input/output for seamless automation

MOON 400M Full Specifications:

• Type: Mono (monoblock) power amplifier
• Circuit / Configuration: Fully Balanced Differential, Mono
• Class of operation: A/AB
• Class A output: Up to 10 watts
• Output power @ 8Ω: 400 W
• Output power @ 4Ω: 650 W
• Gain: 36 dB
• Frequency response (full range): 10 Hz – 125 kHz (+0 / −3 dB)
• Signal-to-noise ratio: 106 dB @ full power
• Input sensitivity: 800 mV RMS
• Input impedance: 47,500 Ω
• Intermodulation distortion: 0.02%
• THD (20 Hz – 20 kHz @ 1 W): 0.02%
• THD (20 Hz – 20 kHz @ 400 W): 0.05%
• Power supply transformer: 400 VA
• Power supply capacitance: 85,000 µF
• Output device type: MOON Bipolars (precision matched proprietary MOON bipolar output transistors)
• Power consumption @ idle: 36 W
• AC power requirements: 120V / 60Hz or 240V / 50Hz
• Fuse replacement: 120V version uses 8A fast blow (3AG); 230V version uses 4A fast blow (3AG)
• Balanced XLR pin assignment: Pin 1 = Ground; Pin 2 = Positive; Pin 3 = Negative
• Dimensions (W × H × D): 16.9 × 3.5 × 14.0 in / 42.9 × 8.9 × 35.6 cm
• Shipping weight: 33 lb / 15 kg
• Connectivity / control: Balanced XLR input, single-ended RCA input, RS-232 port, 12V trigger input & output
• In the box: AC power cable; Owner’s manual; Warranty & product registration information (USA and Canada only)

MOON 400M Q&A:

Does the MOON 400M work as a stereo amplifier on its own?

No—each 400M is a monoblock (one channel). You’ll use two 400M units for a complete stereo setup.

How much power does the 400M deliver into 8-ohm and 4-ohm speakers?

It delivers 400W into 8Ω and 650W into 4Ω, providing strong headroom and control for demanding speakers.

Can I use balanced XLR or RCA inputs?

Yes—there is one balanced XLR input and one single-ended RCA input. You operate in one mode at a time.

What makes the 400M sound controlled and dynamic?

Its design emphasizes a high damping factor, fully balanced differential circuitry, and a large toroidal-based power supply, helping maintain speed, grip, and tonal accuracy.

Does it run in Class A?

It operates in A/AB, with Class A output to 10 watts to enhance finesse and smoothness at lower listening levels.

Is it suitable for custom installation and automation?

Yes—there’s an RS-232 port and 12V trigger input/output, making it easy to integrate into control systems and trigger chains.

What are the power requirements and idle consumption?

It supports 120V/60Hz or 240V/50Hz, and consumes 36W at idle.

What comes in the box?

You’ll receive an AC power cable, the owner’s manual, and warranty/registration information (USA & Canada only).

MOON 400M Downloads:

MOON 400M Manual
MOON Power Amplifier Comparison Chart