Fosi Audio GR70
- Fosi Audio
Fosi Audio GR70
- Fosi Audio
$181.70
- Authorized Dealer · Tech Support · 30-Day Returns
Why it stands out
Best for
Not ideal for
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Setup guide
How to connect
What you should know
EMiUZEK buying notes
Frequently asked questions
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Official product information provided by Fosi Audio
The following product descriptions, specifications and images are provided by the manufacturer.
Fosi Audio GR70 is a Class-A tube headphone amplifier and RCA preamplifier for analog desktop and HiFi systems.
A two-stage four-tube circuit, dual headphone outputs, selectable impedance modes and tone controls provide warm analog listening for headphones or downstream amplifiers.
Why it stands out
Pure tube amplification
Two 5654W and two 6Ж4/6Ж8 tubes form a two-stage analog amplification path.
Headphone and preamp functions
Use 3.5mm or 6.35mm headphones, or connect the RCA output to powered speakers or a power amplifier.
Selectable impedance modes
Low and high settings support headphones from 16Ω to 300Ω.
Direct analog tone control
Front-panel bass, treble and volume adjustment simplify sound tuning without software.
Best for
- Analog headphone listening
- High-impedance and conventional full-size headphones
- Adding tube character before a power amplifier
- Powered speaker systems with RCA input
Not ideal for
- USB, optical, coaxial or Bluetooth sources without a separate DAC
- Directly driving passive speakers
- Balanced headphone or XLR systems
EMiUZEK Buying Notes
- GR70 is an analog headphone amplifier/preamp; digital sources require a DAC with RCA output.
- Its RCA output cannot power passive speakers directly; use powered speakers or a power amplifier.
- Use only officially confirmed compatible tubes and allow installed tubes to cool before handling.
Frequently asked questions
Does GR70 include a DAC?
No. It accepts analog RCA input.
Can it power passive speakers?
No. A separate power amplifier is required.
Which headphones are supported?
The official specification covers 16–300Ω using selectable low/high impedance modes.
Does it have balanced output?
No. Headphone outputs are 3.5mm and 6.35mm, with RCA pre-output.
Can it be used as a preamplifier?
Yes, through the rear RCA output.
Which tubes are supplied?
The official package lists two 5654 tubes and two 6Ж4/6Ж8 tubes.
HOW TO CONNECT
Analog headphone system
Source icon: streamer
Source: DAC / streamer with RCA output
Connection: RCA line input
Output connection: 3.5mm or 6.35mm output
Target icon: headphones
Output: Wired headphones
Powered speaker system
Source icon: streamer
Source: Analog source / DAC
Connection: RCA line input
Output connection: RCA pre-output
Target icon: speakers
Output: Powered speakers
Separate power amplifier system
Source icon: streamer
Source: Analog source / DAC
Connection: RCA line input
Output connection: RCA pre-output
Target icon: amplifier
Output: Power amplifier driving passive speakers
Technical Specifications
Analog connections
| Feature | Specification |
|---|---|
| Input | RCA line input |
| Outputs | RCA pre-output; 3.5mm and 6.35mm headphone outputs |
| Amplification | Class-A tube |
| Tube complement | 2 × 5654W; 2 × 6Ж4/6Ж8 |
Headphone and power
| Feature | Specification |
|---|---|
| Rated output | 90mW @ 32Ω |
| Maximum output | 300mW @ 32Ω |
| Headphone impedance | Low: 16–120Ω; High: 120–300Ω |
| RCA output level | 1.2V |
| SNR | ≥97dB |
| Power input | DC 12V / 3A |
Additional Product Content
Comparison: Which Fosi Audio model is right for you?
| Model | GR40 | GR70 | K7 |
|---|---|---|---|
| Product position | Tube DAC / headphone amp / preamp | Analog tube headphone amp / preamp | Balanced digital DAC / headphone amp |
| Digital inputs | USB, optical, coaxial, Bluetooth | None | USB, optical, coaxial, Bluetooth |
| Headphone outputs | 3.5mm | 3.5mm and 6.35mm | 3.5mm and 4.4mm balanced |
| Speaker-system output | RCA pre-out | RCA pre-out | RCA line output |
| Best use | Digital sources with tube stage | Analog tube headphone system | High-output HiFi and gaming |
What's in the box, manuals and downloads
Shipping, warranty and returns
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Please contact EMIUZEK before returning any product so we can provide assistance.