Fosi Audio GR70 Tube Headphone Amp

The Fosi Audio GR70 is a compact tube headphone amplifier designed to deliver warm, rich sound with classic analog character. Built for audiophiles, it combines vacuum tube performance with modern flexibility, making it ideal for both headphone listening and integration into larger audio systems.

Equipped with two 6K4 vacuum tubes, the GR70 enhances audio with smooth tonal warmth and improved dynamics. Its design provides a natural and engaging listening experience, bringing out detail and depth across a wide range of music genres.

The amplifier supports both 3.5mm and 6.35mm headphone outputs and accommodates headphones from 16 to 300 ohms. A convenient mode switch allows users to toggle between headphone amplifier mode and preamp output, offering versatile use with powered speakers or amplifiers.

Housed in a solid aluminum chassis, the GR70 ensures durability and low-noise performance. The tube-swapping design allows users to experiment with different sound signatures, making it a flexible choice for enthusiasts.

Features
Dual 6K4 Vacuum Tubes
Warm Analog Tube Sound
3.5mm And 6.35mm Headphone Outputs
Supports 16Ω To 300Ω Headphones
Selectable Headphone Amp Or Preamp Mode
RCA Input And Output
Low Noise Power Design
Tube Rolling Capability

Compatibility
Headphones 16Ω To 300Ω
Audio Sources With RCA Output
Powered Speakers And Amplifiers

Specifications
Rated Power Output: 300mW @ 32Ω Max
Signal-To-Noise Ratio: >97dB
Distortion: RCA OUT ≤0.26% PHONE OUT ≤0.5%
Frequency Response: 20Hz-20kHz
Input Impedance: 16Ω-120Ω Low 120Ω-300Ω High
Input: RCA
Outputs: RCA 6.35mm 3.5mm Jack
Power Requirements: 12V/3A

Dimensions & Weight
Dimensions: 12.9 × 19.2 × 4.6 cm

In The Box
12V/3A Power Supply
User Manual