Fosi Audio GR70 Tube

Product detailed description

The Fosi Audio GR70 is a desktop tube amplifier designed for music lovers looking for a natural, warm and musical sound. It combines the functions of a headphone amplifier and an analogue preamplifier, so you can use it for headphone listening or as a source of tube character for your whole hi-fi system.

Tube architecture

The GR70 uses four tubes – two small 5654W preamplifier tubes and two 6AC7 power tubes. The result is gently rounded highs, full mids and a richer low end, typical of tube sound. The added depth and texture of instruments create a musical experience that digital amplifiers often can't replicate.

Ready for different headphones

The amplifier lets you switch between modes for low impedance (e.g. 16–120 Ω) and high impedance (e.g. 120–300 Ω). This means it handles both sensitive modern headphones and more demanding open-back models. Depending on the setting, the output power is sufficient even for demanding headphones that need more drive.

Practical controls and connectivity

On the front panel you'll find 3.5 mm and 6.35 mm headphone outputs, so you don't need any adapters. On the back there are RCA inputs and an RCA output for use as a preamplifier. Bass and treble controls let you fine-tune the sound to your liking, while a solid metal chassis ensures stable operation and optimal cooling.

Key features

• Four tubes (2× 5654W + 2× 6AC7) for authentic tube sound

• Headphone amplifier and preamplifier in one device

• Modes for low- and high-impedance headphones

• 3.5 mm and 6.35 mm outputs for wide compatibility

• RCA input and output for connecting to a hi-fi system

• Bass and treble controls for fine-tuning the character

• Robust ventilated metal chassis

Who is the GR70 ideal for?

• Listeners who want tube colouration and a musical presentation

• Owners of several types of headphones with different impedances

• Smaller hi-fi setups or desktop audio

• Users who prefer analogue controls and visible tubes

Box contents:

Official Fosi Audio GR70 website