Fostex HP-A3 mk2

The Fostex HP-A3 mk2 represents a significant evolution in the field of digital-to-analog audio converters (DACs) paired with a headphone amplifier. This compact model combines functionality, performance, and portability to satisfy both audiophiles and sound professionals seeking a high-quality listening solution.

A Redesigned Technical Architecture

At the heart of the HP-A3 mk2 lies the ESS Sabre 32-bit ES9016K2M converter, a high-performance DAC chip that marks a major improvement over the previous model. This component now allows processing of high-resolution audio signals up to 24-bit/192 kHz via USB connection, compared to 96 kHz for the original version. This increase in maximum sampling rate results in a more faithful reproduction of sound nuances and better stereo imaging.

The amplification stage has also been optimized to deliver superior performance in terms of total harmonic distortion (THD) and signal-to-noise ratio. These technical improvements enable the HP-A3 mk2 to deliver a more transparent and detailed sound, particularly noticeable with high-quality recordings.

Versatile Connectivity and Extended Features

The HP-A3 mk2 features comprehensive connectivity, making it a remarkably versatile device. Its rear panel includes a USB Type-C port that serves as both a digital audio input and power supply, an optical S/PDIF input for external digital sources, an optical S/PDIF output to relay the digital signal, and analog outputs via RCA connectors.

On the front, there is a standard 6.3 mm headphone jack capable of delivering up to 100 mW at 32 ohms and 20 mW at 300 ohms, effectively powering a wide range of headphones, from low-impedance models to more demanding audiophile references.

A “HI/LO” gain switch completes the setup, allowing the output power to be adjusted according to the impedance of the headphones used. In the “HI” position, the gain is increased by 10 dB, optimizing listening with high-impedance headphones that require more power to reach their full potential.

Optimized Audio Performance

Sound quality is the key strength of the HP-A3 mk2. Thanks to its ES9016K2M DAC and carefully designed analog stage, this device offers precise and detailed reproduction, characterized by excellent channel separation and well-defined stereo imaging.

Total harmonic distortion remains below 0.03% at 32 ohms (1 kHz, 100 mW output), reflecting the quality of the amplification stage. The frequency response of 20 Hz to 20 kHz (±3 dB) covers the entire audible spectrum, ensuring faithful reproduction of all instruments and voices.

Compared to its predecessor, the HP-A3 mk2 shows a notable improvement in overall sound quality. The bass is more defined, the mids more natural, and the highs more open, without ever becoming harsh. This tonal neutrality makes it a valuable tool for analytical listening while preserving musical enjoyment.

System Compatibility and Installation

The HP-A3 mk2 is compatible with Windows 10 computers and Mac OS Catalina (10.15) or later versions. On Mac OS, installation is plug-and-play, requiring no additional drivers. On Windows, specific drivers may be needed to fully utilize the device’s capabilities, particularly for high sampling rates.

Power is supplied exclusively via the USB port, with a moderate power consumption of 2.5 W. This feature greatly simplifies installation and use, as no external power supply is required.

Practical Applications

The Fostex HP-A3 mk2 is suitable for various applications:

• Enhancing headphone listening quality from a computer
• Digital-to-analog conversion for external sources (CD players, gaming consoles, TVs)
• Preamplification for audio systems with active speakers or a power amplifier
• Mobile audio monitoring for sound professionals

Its ability to convert both USB and optical S/PDIF signals makes it an ideal central component in a modern digital audio chain.

Technical Specifications

Inputs

• USB Terminal
  • Connector: USB Type-C
  • Interface: USB 2.0 High Speed
  • Compatible Operating Systems: Windows 10, Mac OS Catalina (OS 10.15) or later
  • Sampling Frequencies: PCM max. 192 kHz
• Digital Input
  • Connector: Optical, Square
  • Format: S/PDIF (32 kHz – 96 kHz)

Outputs

• Headphone Terminal
  • Connector: Standard 6.3 mm stereo jack
  • Maximum Output Power: 100 mW (32 Ω), 20 mW (300 Ω)
  • Load Impedance: Greater than 16 Ω
  • THD: Less than 0.03% (at 32 Ω, 1 kHz, 100 mW output)
  • Frequency Response: 20 Hz – 20 kHz ±3 dB
• Analog Output L, R
  • Connector: RCA Connector
  • Maximum Output Level: 2 V RMS (0 dBFS VR: MAX)
  • Applicable Load Impedance: Greater than 10 kΩ
  • THD: 0.005% (at 1 kHz)
  • Frequency Response: 20 Hz – 20 kHz ±3 dB
• Digital Output
  • Connector: Optical, Square
  • Format: S/PDIF

General Specifications

• Accessories: USB Cable (Type-A to Type-C, 1 m) × 1, Rubber Feet × 4
• Dimensions: 34 (H) × 113 (W) × 155 (D) mm, including protrusions, excluding feet
• Weight: Approximately 500 g
• Power Supply: 5 V DC, via USB terminal
• Power Consumption: 2.5 W