STEREO POWER AMPLIFIER

The Strumento N°4 mkII represents the pinnacle of Audia Flight’s amplifier design—a state-of-the-art two-channel amplifier delivering exceptional bandwidth (over 1 MHz), immense output power (up to 900 Watts), and near-limitless control over any loudspeaker. Drawing on the design advancements of its sibling, the Strumento N°8 mono-block amplifier, and guided by countless hours of critical listening, the mkII version refines the original Strumento N°4 with meticulous circuit enhancements. These seemingly minor—but sonically significant—adjustments, such as optimized resistor and capacitor values, bring the amplifier even closer to our goal of absolute musical perfection. Its chassis begins as a bespoke, ultra-high-grade aluminum casting. After CNC machining, each component is hand-inspected and polished to a mirror finish. Key areas undergo additional finishing, including shot peening and anodization, before a final silk-screening completes the elegant aesthetic. Inside, the amplifier’s exclusive Class A current-feedback gain stage is housed in a sealed aluminum enclosure, encapsulated in epoxy resin for thermal stability and isolation from external interference. The output stage is powered by a massive 3000VA custom-made audio transformer, also resin-encased and shielded by dual ferromagnetic layers. Ultra-fast rectifiers replace traditional fuses in the main output power supply, eliminating sonic compromise. Mechanical integrity is also paramount. The power transformer is mounted on a separate, physically decoupled chassis—ensuring that any residual vibration is harmlessly discharged to ground and kept entirely away from the sensitive audio circuitry. Every element inside reflects extreme attention to detail and Italian craftsmanship: fully balanced circuitry, premium components throughout, a massive power supply with 280,000 μF of ultra-low-impedance capacitors, custom PCBs with thick, high-purity copper, and ultra-pure copper bus bars in the output stage. Power delivery is handled by two ultra-high-current supplies per channel, along with four independently regulated stages for each: two for the input section and two for the current-feedback gain stage. The gain stage power supply is engineered for extremely low noise, using ultra-fast rectifiers and precision capacitors. Two 150VA toroidal transformers serve the audio stages, while a separate 15VA transformer powers the logic and protection systems. A total of twenty-eight 10,000 μF / 40V capacitors form the heart of the main power supply. In keeping with Audia Flight’s uncompromising approach, no traditional fuses are used in the output stage’s power supply. Instead, a microprocessor-controlled current sensor ensures protection without introducing unwanted resistance into the signal path. The Strumento N°4 mk2 isn’t just a power amplifier—it’s a reference-grade instrument, crafted to reveal the deepest textures of music with precision, power, and emotional impact.