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Fosi Audio P4 Mini Preamp Review: Compact control for analogue systems

Fosi Audio P4 Mini Preamp with 3 RCA Inputs, Home Audio Stereo Pre amp for Amplifier/Active Subwoofer/Speakers, Preamplifier with 3-Level Adjustable Gain 3/6/9 dB, Bass and Treble Control
4.6
[Multi-Source Hub]  Supports up to 3 RCA inputs for CD players, turntables (phono), streamers and more.
[Easy Audio Control]  Volume, bass/treble, three-level gain and remote for customizable, convenient audio setup.
[Motorized Volume Knob]  High-precision motorized analog pot enables smooth, low-noise volume adjustments with minimal distortion.
[Compact EMI-Resistant Design]  Sleek, space-saving chassis resists electromagnetic interference for reliable, long-term performance.
[Audiophile-Grade Sound]  Low noise floor, high SNR, and ultra-low distortion for pristine, accurate sound reproduction.
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A compact audio preamp that centralises analogue sources while keeping noise to a minimum. Audiophiles who want straightforward switching, motorised remote volume and tone shaping will appreciate the convenience of the Fosi Audio P4 Mini Preamp. Does the minimalist size and feature set suit a more advanced hi-fi system?

⚡ At a Glance
  • Sound Signature: Transparent, low-noise presentation with accurate mids and controlled bass
  • Best for: Home audio enthusiasts and small-system owners seeking clean source switching
  • Not ideal for: Turntable users without a built-in phono preamp

Three RCA inputs allow quick switching between analogue sources, while a motorised potentiometer manages volume quietly. Tone controls, three-level gain and a low noise floor give precise, dependable control for compact stereo setups.


Smooth and precise volume control - with a motorised potentiometer

A high-precision motorised analogue pot enables remote-controlled volume changes with stable channel balance and reduced mechanical noise. The motorised action moves the pot smoothly, avoiding abrupt jumps or clicks.

Accurate level adjustments from the armchair become simple, and quiet operation keeps background noise out of the signal chain.

Flexible source switching and tone shaping - with three RCA inputs and bass/treble controls

Three RCA line inputs accept CD players, streamers, DACs, cassette decks and turntables that include a phono preamp. Dedicated bass and treble controls include a bypass function, and three-step gain (3/6/9 dB) helps match upstream levels.

Easily switch between multiple sources, tailor tonal balance for different recordings and match output levels to amplifiers or active subwoofers.

Clean, interference-resistant output - with minimalist chassis and low-noise circuitry

Circuit design focuses on a low noise floor, high signal-to-noise ratio and very low distortion, while a compact, robust enclosure reduces susceptibility to electromagnetic interference. Component layout minimises crosstalk between channels.

Reliable, clear playback that preserves recording detail, even when used in small racks or near other electronics.

✨ The 4 Key Reasons for Fosi Audio P4 Mini Preamp
  1. Motorised potentiometer, precise remote volume control with minimal channel imbalance
  2. Three RCA inputs, switch multiple sources without reconnecting cables
  3. Three-level gain control, match output to amps or active subs accurately
  4. Bass and treble controls with bypass, shape tone or bypass EQ quickly
📋 Technical Details at a Glance
  • Category: Home audio stereo preamplifier
  • Inputs: 3 x RCA line inputs
  • Gain control: Three-level adjustable gain, 3/6/9 dB
  • Tone controls: Bass and treble adjustment with bypass function
  • Volume control: Motorised analogue potentiometer
❓ Frequently Asked Questions

Q: Can I connect a turntable directly to the preamp?

A: Turntables that include a built-in phono preamp can be connected directly via RCA inputs. Passive turntables without a phono stage will need an external phono preamp first.

Q: Does the unit include a remote for volume and input switching?

A: Yes, a remote is included and supports motorised volume adjustment plus input selection for convenient control from the listening position.

Q: Will it work with an active subwoofer or power amplifier?

A: Yes, three-level gain control helps match output to amplifiers or active subwoofers, allowing level adjustment to suit different systems.

🏆 Our Verdict

The Fosi Audio P4 Mini Preamp suits listeners who want neat, low-noise control of multiple analogue sources in a compact footprint. Motorised volume, three RCA inputs, tone controls and a low-noise design make it a practical centre for modest hi-fi setups. Consider it a long-term value for those prioritising reliable, fuss-free analogue switching and tone shaping.