Integrated Amplifier MOON by Simaudio 641 2-Tone

MOON 641 integrated amplifier with dual-mono architecture and MDCA circuitry

The MOON 641 is an integrated amplifier that combines a preamplifier and a power stage in a single chassis, forming the heart of an audio system. It joins the North Collection series and is built around a dual-mono configuration delivering 125 W into 8 Ω and 250 W into 4 Ω. Distortion is kept in check by the MDCA (MOON Distortion-Cancelling Amplifier) circuit, which operates outside the signal path and requires no global negative feedback. The unit is designed and assembled in Québec, Canada.

The construction emphasises a carefully considered internal board layout and vertical heatsinks that contribute to both thermal and mechanical stability. Volume is handled by the third-generation M-VOL3 electronic gain control, which maintains precise channel tracking and fine increments even at low listening levels. Operation is made easy by a 4.3" colour LCD display together with front-panel controls and the supplied BRM-1 intelligent remote. The rear panel offers line-level inputs, a line output and clearly spaced speaker terminals.

The measured figures confirm its grip on the load: a damping factor of 700, 109 dB signal-to-noise ratio, 2 Hz – 90 kHz frequency response (+0/–3 dB), THD+N of 0.003 % at 125 W and crosstalk of –109 dB. The high damping factor translates into firm, well-defined bass across a wide range of loudspeakers, while the low noise and distortion support detail resolution and stable instrument placement within the stereo image. A robust power supply preserves signal integrity from the inputs all the way to the binding posts.

The amplifier also features the MOONLink interface for coordination with other North Collection components — its natural partner is the MOON 681 network player and DAC, with which the 641 forms a complete system. An energy-saving standby mode drawing 2.5 W is available as well. The 641 and 681 pairing received a Golden Ear Award from The Absolute Sound magazine (2025).

Key features

• Power output: 125 W/8 Ω and 250 W/4 Ω in dual-mono configuration
• MDCA: Distortion cancellation without global negative feedback
• M-VOL3: Precise third-generation electronic gain control
• Damping factor 700: Firm control over the loudspeaker load
• MOONLink and display: North Collection integration and a 4.3" colour display