Fosi Audio P4 HiFi Preamplifier: 3 RCA Inputs, EQ/Bypass, Swappable Op-Amps, Treble & Bass Tone Control For Audiophile Systems

Fosi Audio P4 HiFi Preamplifier: 3 RCA Inputs, EQ/Bypass, Swappable Op-Amps, Treble & Bass Tone Control For Audiophile Systems

Features:

Studio-Level Signal Accuracy | ±0.1dB Frequency Response & 105dB SINAD

Pure, untainted reference-quality sound, tailored for discerning ears.

With a flat frequency response from 20Hz to 20kHz (±0.1dB) and a 105dB SINAD (Signal-to-Noise Ratio + Distortion), the P4 achieves nearly lossless signal transmission. Featuring Japanese Elna audio capacitors and Omron gold-plated signal relays, it eliminates current noise to ensure every detail is faithfully reproduced, rivaling the performance of high-end preamps costing tens of thousands.

Three-Input Hub | One-Touch Switch Between CD, Vinyl, and DAC

Say goodbye to constant plugging and unplugging, and build a multi-device Hi-Fi system.

Three independent RCA inputs allow you to simultaneously connect a turntable (with external phono preamp), CD player, and high-end DAC. With the infrared remote, you can easily switch between sources with a single button press. Whether you’re enjoying your classic vinyl collection or streaming Hi-Res music, simply press a button to experience seamless listening.

Gain Staging + Motorized Potentiometer | Precision Matching for Power Amplifiers

Perfectly adaptable from low-sensitivity to high-resolution systems.

3dB/6dB/9dB Gain Adjustment:

▸ Low Gain (3dB): Protects sensitive power amplifiers from overload distortion.

▸ High Gain (9dB): Reduces system noise floor and enhances dynamic range.

The ALPS vintage motorized volume knob uses an analog potentiometer structure with left-right channel error <0.1dB, ensuring smooth, unbiased volume control.

Tone Control Freedom | Adjustable EQ + Replaceable Op-Amps + Bypass Mode

From precise monitoring to personalized sound tuning, a dual-purpose machine.

Midpoint-adjustable bass and treble: Compensate for room acoustics or enhance rock/jazz atmospheres.

Hi-Fi Bypass Mode: Direct signal path with the EQ circuit bypassed, delivering uncolored, high-resolution sound.

Replaceable op-amp design: Compatible with popular dual-op-amp chips (such as MUSES02/OPA2604), allowing you to easily customize the sound signature to your preference—whether it's a "warm tube-like" or "crisp, analytical" tone.

Minimalist Control Aesthetic | Full-Function Remote + Compact Metal Chassis

Ideal for both desktop and rack setups, blending seamlessly into high-end systems.

Comprehensive remote control: Power on/off, switch inputs, and adjust volume/mute without the awkward "bending over to find the knob" experience.

PRE OUT Output: Connect an active subwoofer for a 2.1 system, or link multiple amplifiers for multi-room audio.