Fosi Audio GR70 Tube Headphone Amplifier and Preamplifier with GE 5654W Vacuum Tubes and Bass Treble Controls

Whether you are using it to drive your favorite pair of headphones or as a dedicated preamp for your active speakers, the GR70 adds a layer of harmonic depth and airiness to your audio chain.

Housed in a rugged, CNC-machined aluminum alloy chassis with a striking industrial aesthetic, the GR70 is built for both performance and longevity. It features independent bass and treble tone controls, allowing you to fine-tune your sound to match your specific headphones or room acoustics. With support for a wide range of headphone impedances and a dedicated RCA output, this versatile unit is the perfect centerpiece for audiophiles looking to integrate the timeless charm of tube amplification into a modern desktop environment.

Authentic Vacuum Tube Warmth: Utilizes a quad-tube configuration with GE 5654W tubes to provide a smooth, analog sound that enhances vocal clarity and instrument separation.

Dual-Purpose Functionality: Acts as a powerful headphone amplifier and a high-fidelity preamplifier, making it easy to integrate into both headphone and speaker-based systems.

Precision Tone Customization: Features dedicated bass and treble knobs with a center-point detent for flat response or personalized frequency adjustments.

Versatile Headphone Support: Equipped with 3.5mm and 6.35mm outputs to accommodate standard and professional-grade headphone cables without the need for adapters.

Switchable Impedance Optimization: Includes a dedicated toggle for high and low impedance settings to ensure a perfect match for sensitive IEMs or demanding over-ear headphones.

High-Quality Components: Built with premium resistors and capacitors to ensure a low-noise floor and transparent signal transmission.

Durable Aluminum Construction: The sandblasted CNC aluminum housing provides excellent heat dissipation and protects the internal circuitry from external interference.

User-Replaceable Tubes: Designed with a plug-and-play tube architecture, allowing enthusiasts to experiment with different 5654W, 6J1, or 6K4 tubes for sound tuning.

Specifications:

Amplifier Type: Vacuum Tube (Class A)

Included Tubes: 2x GE 5654W and 2x 6AK5

Headphone Outputs: 3.5mm Single-ended and 6.35mm (1/4 inch) Stereo

Analog Inputs: Stereo RCA

Analog Outputs: Stereo RCA (Pre-out)

Maximum Power Output: 300mW per channel at 32 Ohms

Headphone Impedance Range: 16 Ohms to 300 Ohms

Frequency Response: 20Hz to 20kHz (plus or minus 1dB)

Signal to Noise Ratio: 97dB

THD: Less than or equal to 0.5 percent

Power Supply: DC 12V

Chassis Material: Aluminum Alloy