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Description
Fosi Audio GR70 Tube Headphone Amp – Vintage Warmth, Modern Precision
The Fosi Audio GR70 is a premium quad-tube headphone amplifier and preamp that blends the classic charm of vacuum tube audio with the precision of modern engineering. Featuring two 5654W and two 6Ж4 replaceable vacuum tubes, it delivers a rich, warm, and immersive listening experience that brings music to life.
Its dual-stage amplification ensures exceptional clarity and tonal depth—5654W tubes boost voltage for smooth mids and highs, while 6Ж4 tubes handle power amplification for dynamic, textured bass. Whether you’re pairing with over-ear headphones, IEMs, or a full Hi-Fi system, the GR70 adapts effortlessly.
With low and high impedance modes (16Ω–300Ω), multiple headphone outputs (6.35mm & 3.5mm), and RCA input/output for preamp functionality, the GR70 fits seamlessly into any audio setup. The large top-mounted volume knob, bass & treble tone controls, and dual-side ventilation make it both functional and stylish.
Built from CNC-machined aluminum alloy, this compact yet powerful amp outputs up to 300mW @ 32Ω, offering a signal-to-noise ratio ≥97dB for clean, distortion-free sound. The Fosi Audio GR70 is the perfect choice for audiophiles seeking authentic tube warmth without compromising detail or precision.
Specifications
Model: Fosi Audio GR70
Type: Tube Headphone Amplifier & Preamp
Tubes: 2 × 5654W, 2 × 6Ж4 (replaceable)
Input: RCA
Outputs: RCA, 6.35mm, 3.5mm headphone jacks
Max Power Output: 300mW @ 32Ω
Power Input: DC 12V/3A
Headphone Impedance:
• Low Mode: 16Ω–120Ω
• High Mode: 120Ω–300Ω
Output Voltage (RCA): 1.2V
SNR: ≥97dB
Controls: Volume knob, bass & treble tone controls, high/low impedance switch
Body Material: CNC-machined aluminum alloy
Design Features: Dual-stage amplification, dual-side ventilation, compact form factor











