The Fosi Audio GR70 is a Class A, output-transformerless tube headphone amp and preamp with two 5654W voltage tubes and two 6Zh4/6Zh8 power tubes, rated 90mW (300mW max) into 32Ω, plus 6.35mm and 3.5mm headphone jacks and an RCA preamp output. It suits listeners who want tube amplification for 16–300Ω headphones, or a tube stage between a DAC and powered speakers or a power amp.
Who the Fosi Audio GR70 is for
Headphone listening: A Hi-Z/Lo-Z switch matches 16–120Ω or 120–300Ω headphones, and the front panel has both 6.35mm and 3.5mm jacks.
Tube preamp duty: RCA in and a 1.2V RCA out let it sit between a DAC or CD player and powered speakers or a power amplifier.
Tube rolling: All four tubes are replaceable, and 6AC7 or CV849 tubes can substitute for the 6Zh4/6Zh8 power tubes.
Tone shaping: Bass and treble knobs with center detents work whether you use the headphone jacks or the preamp output.
Skip it if: You need a DAC or Bluetooth; the GR70 is analog-only with a single RCA input, so digital sources need a separate DAC.
Fosi Audio GR70 key specs
Amplifier type: Class A, output-transformerless (OTL) tube headphone amp and preamp
Headphone power: 90mW @ 32Ω rated, 300mW @ 32Ω max
Headphone impedance: Lo-Z 16–120Ω, Hi-Z 120–300Ω
Connections: RCA in; RCA out (1.2V); 6.35mm and 3.5mm headphone jacks
Tone controls: Bass and treble with center detents
SNR / frequency response: ≥97dB / 20Hz–20kHz (±1dB)
Power: DC 12V/3A adapter, included
Size: 187 × 129 × 42 mm
In the box: GR70, 2 × 5654 tubes, 2 × 6Zh4/6Zh8 tubes, 2 tube protection covers, 12V/3A power supply, user manual
Genuine Fosi Audio stock. Free shipping on every order, 45-day returns.
Fosi Audio GR70 vs similar options
vs xDuoo TA-10R: Adds a built-in AK4493EQ DAC with XMOS USB input and DSD playback; pick the GR70 if your source already has a DAC and you want a quad-tube amp for less.
vs xDuoo MH-02: Costs less and adds a CS43131 USB DAC with DSD256 decoding; pick the GR70 for four tubes in two stages plus bass and treble controls.
Yes. Every unit we sell is genuine and brand-new, shipped in its original packaging, and backed by our 1-year TonePier warranty and 45-day returns.
Where does my order ship from, and how long does it take?
Every order ships from our warehouse in China, with full tracking, and most orders ship within 3 business days. Shipping is free on every order; most US orders arrive within 7–15 business days and most orders to other countries within 7–20 business days — see our shipping policy for details.
What if it isn't for me?
You get 45 days to decide. Keep the packaging, keep it in like-new condition, and send it back for a refund. Ear tips unsealed for hygiene reasons are fine — we expect you to actually listen.
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