Momentum M400 MxV Monoblock Amplifier

One iconic amplifier continues to lead, elevating Dan D’Agostino Master Audio Systems’ original amplifier design, while featuring techniques and topologies initially developed and implemented in the Relentless Series. This fullest expression of the Momentum circuitry is reflected in the model’s name, MxV. Those with a physics background will recognize that its name MxV, or Mass times Velocity, is the equation for Momentum.

Every major section of the amplifier—power supply, input, driver, and output stages—has been enhanced. An improved transformer winding provides over 50% more current output from the same transformer footprint, offering greater headroom during dynamic passages. The input stage combines revised circuit topology with advanced components feeding the driver and output stages. Crucial to the new circuit are bipolar transistors powering the front end that deliver ten times the current and power of the originals. These wider bandwidth, higher-power components extend low- and high-frequency performance with reduced distortion at both frequency extremes.

Energizing the driver stage is a bias stability circuit providing a nearly 50% increase in operating bias. Increasing Class A operation directly correlates to better sound quality. However, there is a limit to bias level in any amplifier. With this new circuit topology and unique copper heatsinks, thermal issues are not a practical concern, preventing excessive temperatures even under the greatest demand. Additional power transistors in the output stage reduce workload for each device, so the entire output section works more efficiently. The result is a richer, more dynamic, and intimate presentation of the music.

The final output stage features 28 new high-output transistors originally sourced for the flagship Relentless Series amplifiers. Among the fastest available, these run at a blistering 69 MHz and permit the amplifier to achieve incredible bandwidth. Each transistor mounts with two stainless steel fasteners—a rarity among flat-package transistors—for maximum thermal transfer to the copper heatsinks. A capacitor/resistor network connected to the base of each transistor ensures stability even at high frequencies and with low-impedance speakers. Additionally, every output transistor is measured, and only devices that match the required performance specifications are used. As with all D’Agostino models, the Momentum M400 MxV Monoblock Amplifier features discrete, direct-coupled balanced circuitry, the most accurate circuit platform possible.