Fosi Audio Box X2vsFosi Audio Box X4
A detailed side-by-side comparison of the Fosi Audio Box X2 and Fosi Audio Box X4 — two popular preamps in the Chinese HiFi space.
Specifications
Spec
Fosi Audio Box X2
Fosi Audio Box X4
Tubes
6J2 × 2 (Replaceable with 5654W)
Jan5654W × 2
Topology
Phono Preamp (MM) + Tube Buffer
Phono Preamp (MM) + Tube Buffer
Inputs
Phono (MM) RCA
Phono (MM), Bluetooth 5.0
Outputs
RCA
RCA, 3.5mm Headphone
Features
Adjustable Gain Settings (39/42/45 dB)
Bass/Treble Controls, Ground Post
Remote Control
✗
✗
Tube Stage
✓
✓
Phono Stage
✓
✓
Headphone Amp
✗
✓
Price (estimated)
Price
~$69
~$79
Difference
~$10.00 cheaper (Fosi Audio Box X2)
Things to Know
Fosi Audio Box X2
- ⚠No power switch on the front (toggle switch is on the cable or back depending on revision).
- ⚠Stock tubes (6J2) are often microphonic; upgrading to GE 5654W or Riverstone tubes is almost mandatory.
- ⚠Can introduce hum if placed too close to power amplifiers or WiFi routers.
Fosi Audio Box X4
- ⚠Headphone output is relatively weak and can sound thin with high-impedance headphones.
- ⚠Tube sockets are extremely tight; changing tubes requires significant force and care.
- ⚠Bluetooth input is 'always on' and can be hijacked by neighbors if not paired.
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