Esoteric F-01 Reference Class A Stereo Integrated Amplifier

Class A Integrated Amplifier F-01 Delivers Reference-Grade Sonic Purity

Class A Integrated Amplifier F-01 is a flagship-grade high-fidelity amplifier that redefines the limits of what an integrated amplifier can achieve. Developed by Esoteric and infused with the same core technologies as their Grandioso “X” Edition separates, the F-01 offers elite preamp and power amp performance in a unified chassis. It stands as the ideal companion to Esoteric’s K and N Series digital source players and sets an unprecedented benchmark for audiophiles seeking musicality, transparency, and expandability from a single enclosure.

F-01 Integrates Grandioso C1X-Level Preamplifier Design

F-01 Class A Integrated Amplifier is equipped with a balanced dual mono preamplifier directly inspired by the flagship Grandioso C1X, bringing unparalleled precision and signal purity to integrated design. Featuring three ES-Link Analog inputs, it facilitates proprietary current-based signal transmission from Esoteric digital players, bypassing the limitations of voltage-based interconnects.

At the core of this preamp is Esoteric’s Ultra Fidelity Attenuator System, a high-supply voltage stepped attenuator capable of an extraordinary 0.1dB resolution across 1,120 discrete steps. Developed using the proprietary UFA-1792 module, this mechanism delivers a level of granular control and linearity that vastly exceeds conventional volume systems, preserving dynamic range while optimising signal-to-noise performance.

Additionally, the dual mono phonostage preamp supports both MM and MC cartridges, featuring completely independent left and right signal paths and power supplies for absolute channel separation. A fully balanced headphone amplifier, operating at up to 600mW into 32Ω, provides balanced 4-pin XLR and unbalanced 6.3mm outputs, enabling audiophile-grade private listening.

F-01 Implements Esoteric’s ES-Link Analog for Current-Based Signal Transmission

F-01 Integrated Amplifier introduces three switchable ES-Link Analog inputs, Esoteric’s proprietary current signal transmission protocol. By transmitting audio as current rather than voltage, ES-Link Analog overcomes interconnect cable impedance issues, ensuring consistent signal delivery even across long distances. This technology offers a vivid, live studio-monitoring sound, preserving micro-detail, spatial cues, and transient integrity with unmatched stability.

In a “high out, low in” configuration, the output impedance of ES-Link Analog devices sits around 1kΩ, while the input impedance approaches 0Ω. This configuration enables current flow that is over 100 times greater than conventional voltage transmission, resulting in full energy delivery across the entire bandwidth—critical for conveying the emotional power of music.

F-01 Houses a Grandioso-Level Power Supply Architecture

F-01 Integrated Amplifier features a dual mono power rectification layout and a 940VA EI-core power transformer—unusually large for an integrated unit—directly lifted from Esoteric's reference-grade amplifiers. This bare-mounted transformer offers increased capacity and reduced mechanical noise due to the omission of housing, allowing it to deliver instantaneous current to the amplifier circuits during high-demand transients.

Capacitor configuration includes four Grandioso-grade 10,000μF block capacitors per channel, operating in parallel with staggered charging and discharging sequences. This ensures linear current supply and enhances both low-end control and treble extension. The internal busbars and conductor paths are constructed with thick, high-purity OFC copper, while signal routing is optimised with ultra-low-impedance architecture, reducing losses and improving drive capability—particularly for large, demanding loudspeakers.

F-01 Class A Amplification Circuit Mirrors the Grandioso S1X Design

F-01 Class A Integrated Amplifier delivers 30 watts per channel into 8Ω in pure Class A, and 60 watts per channel into 4Ω, ensuring constant high-current operation for smooth, rich harmonic content and zero crossover distortion. The topology draws heavily from the Grandioso S1X stereo amplifier, with a straightforward, minimalist signal path that eliminates unnecessary components.

The amplification stage uses a bipolar transistor 3-parallel push-pull configuration, and its phase compensation circuit is reduced to a single-pole design. NFB (negative feedback) is kept to a minimum, allowing natural decay, overtones, and subtle dynamics to breathe. This purist approach results in superior harmonic reproduction and astonishing realism, matching and even surpassing many standalone amplifiers.

F-01 Achieves Mechanical Stability Through Advanced Chassis Design

F-01’s chassis engineering is meticulously optimised to control vibration-induced distortions and protect signal integrity. At 32 kg, the enclosure’s mass and rigidity rival separate amplifier systems. It features a semi-floating top panel to reduce resonances and isolate the audio path from mechanical stress. Esoteric’s patented isolation feet—combining spike and saucer—further decouple the amplifier from external vibration.

The amplifier block’s custom wave-shaped heat sinks are engineered to disperse resonance peaks, aiding in both cooling and mechanical damping. These structural refinements ensure that the signal path remains uncorrupted by environmental noise or internal vibration, preserving the sonic microstructure of recordings.

F-01 Offers Expansive Flexibility and Seamless System Integration

F-01 Integrated Amplifier is engineered with high system expandability in mind. Audiophiles can connect Esoteric’s PS-01F external power supply via the dedicated DC input to elevate preamp performance to Grandioso C1X levels. Likewise, the amplifier’s ES-Link Analog and XLR pre-outs support connection to the S-05 Class A power amplifier for advanced bi-amplification configurations or multi-amp setups.

For further customisation, F-01 includes a modular expansion slot compatible with legacy OP-DAC1 and OP-ESLA1 option boards. This enables users to add digital-to-analogue conversion or additional ES-Link inputs, depending on system requirements.

Input gains are independently adjustable in ±18dB (0.1dB increments), with balance control available in the same fine steps. An AV-through output ensures seamless integration with home cinema setups, enabling volume bypass operation when required.

F-01 Combines Exceptional Usability with Luxurious Interface Design

F-01’s user interface balances minimalism and functionality. The front panel is cleanly arranged, featuring Grandioso-grade high-precision control knobs that rotate with exquisite tactile feedback, thanks to internal ball bearings. Machined from solid aluminium, these controls exude both durability and refinement.

The remote control (RC-1339), also made from aluminium, provides universal functionality for Esoteric SACD players and network devices. Additional features include programmable input names, display dimmer, automatic display-off, volume fade-in/out, and mute—all contributing to a refined user experience that reflects the amplifier’s audiophile focus.

Control protocols include RS-232C, trigger input/output, and comprehensive logic isolation using photocouplers and isolators. This separation between control and audio signal paths ensures that the digital control systems never interfere with the analogue signal purity, even during dynamic operation.