The Head Box S3 B sits at the top of Pro-Ject's Head Box headphone amplifier range, positioned above the single-ended Head Box S2 and representing the company's most capable dedicated headphone amplifier in the current line-up. It is designed for audiophiles who require true balanced amplification from a compact, desktop-friendly component.
Fully Balanced Circuit Topology
The Head Box S3 B implements a fully balanced signal path from input to output, accepting both RCA and XLR analogue inputs while maintaining balanced operation throughout the amplifier stages. This results in improved channel separation and lower noise compared with single-ended designs. Balanced headphone connections are provided via a 4.4mm Pentaconn socket and a 4-pin XLR, while single-ended headphones are accommodated through 3.5mm and 6.3mm outputs on the front panel.
Performance Targets
Power output is rated at 480mW into 8 ohms, rising to 820mW into 32 ohms, sufficient for demanding planar magnetic and dynamic headphones alike. The signal-to-noise ratio exceeds 115dB (A-weighted), and total harmonic distortion is below 0.002% at 1kHz, placing the Head Box S3 B firmly in the high-performance category at its price point.
Enclosure and Finish
The amplifier is built into a full aluminium enclosure, providing mechanical stability and effective electromagnetic shielding. The Silver finish features a brushed aluminium faceplate, complementing Pro-Ject's existing turntable and phono stage range.
