Fosi Audio Box X4vsFosi Audio SK01
A detailed side-by-side comparison of the Fosi Audio Box X4 and Fosi Audio SK01 — two popular preamps in the Chinese HiFi space.
Specifications
Spec
Fosi Audio Box X4
Fosi Audio SK01
Tubes
Jan5654W × 2
—
Topology
Phono Preamp (MM) + Tube Buffer
Solid State Op-Amp
Inputs
Phono (MM), Bluetooth 5.0
3.5mm Line In
Outputs
RCA, 3.5mm Headphone
3.5mm Line Out, 3.5mm/6.35mm Headphone
Features
Bass/Treble Controls, Ground Post
Hardware Loudness Switch, 3-Band EQ, High/Low Gain
Remote Control
✗
✗
Tube Stage
✓
✗
Phono Stage
✓
✗
Headphone Amp
✓
✓
Price (estimated)
Price
~$79
~$70
Difference
~$9.00 cheaper (Fosi Audio SK01)
Things to Know
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.
Fosi Audio SK01
- ⚠Built-in battery is unnecessary for a desktop unit and will eventually degrade/fail.
- ⚠Input is limited to a single 3.5mm jack (no RCA inputs without adapter).
- ⚠Form factor is tall and narrow, making it easy to tip over when heavy cables are attached.
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