THE FOSI AUDIO GR70 TUBE HEADPHONE AMP IS A COMPACT QUAD‑TUBE AMPLIFIER WITH PRE‑AMP FUNCTION

Fosi Audio has added the Fosi Audio GR70 Tube Headphone Amp to its Portable Headphone Amplifier range.

It combines tube-based amplification with desktop portability, offering both headphone amplification and preamp capabilities.

FOSI AUDIO GR70 TUBE HEADPHONE AMP

The Fosi Audio GR70 Tube Headphone Amp incorporates a quad‑tube configuration featuring two 5654W and two 6Ж4 vacuum tubes. According to the product description, the arrangement uses the 5654W tubes for voltage gain and the 6Ж4 tubes for power amplification.

FUNCTIONALITY AND CONNECTIONS

This unit is described as a 2‑in‑1 device, providing both headphone amplification and preamplifier functionality. It includes front-panel outputs via 6.35 mm and 3.5 mm headphone jacks, plus RCA input and output connectors at the rear.

FOSI AUDIO GR70 TUBE HEADPHONE AMP TECHNICAL SPECIFICATIONS

The GR70’s spec sheet lists a maximum output of 300 mW at 32 Ω, powered by a DC 12 V / 3 A adapter. It supports headphone impedance from 16 Ω to 300 Ω, switchable between low (16–120 Ω) and high (120–300 Ω) modes. Additionally, it provides bass and treble controls and a large damped volume knob.

Its chassis is CNC-machined from aluminium alloy with side ventilation for thermal stability. The top panel is perforated to facilitate heat dissipation.

FOSI AUDIO GR70 TUBE HEADPHONE AMP PRICE AND AVAILABILITY

Fosi Audio prices the GR70 at $239.99 USD,

HiFi PiG Says: A great looking and multi-functional Headphone/Pre amp that should appeal to budget audiophiles.