How do I integrate P4 into a audio system?

First, connect P4 to your audio sources via RCA cables, then connect P4 to an amplifier via RCA cables, and lastly, use speaker cables to connect the amplifier to the passive speakers.

What is the function of the Bypass switch?

This is the bypass function for turning the tone control on and off. Sliding it up bypasses the bass and treble adjustments while sliding it down enables the bass and treble controls. The bypass switch won’t function on the volume control.

What are the benefits of the high-precision motorized analog potentiometer in the P4?

It ensures smooth, precise volume control, and enhances usability while reducing noise and distortion. When adjusting the volume with the remote, the potentiometer‘s motor syncs with the physical knob, providing a seamless and intuitive experience.

What can the pre-out port used for?

Allows for easy connection to external powered subwoofers or additional amplification. It ensures seamless integration with your audio system, enabling enhanced bass response or driving additional speakers for a more immersive listening experience.

Fosi Audio P4 Mini Preamplifier - Fosi Audio

Product Highlights

RCA Inputs

≥ 110dB

SNR

≤ 0.003%

THD+N

≥105dB

SINAD

Product Highlights

RCA Inputs

≥ 110dB

SNR

≤ 0.003%

THD+N

≥105dB

SINAD

Fosi Audio P4 Mini Preamplifier

Name: Fosi Audio P4 Mini Preamplifier
Brand: Fosi Audio
SKU: P4-US-12V
Price: 99.99 USD
Availability: InStock

$99.99

176 recensioni totali

Features

Triple RCA Inputs
Bass, Treble, and Gain Control
Motorized Pot for Smooth Adjustment
Bypass Function for Pure Signal Path
Op-Amp Rolling: SS3602, MUSES02, OPA2134PA

Varianti di prodotto

Review Videos

Finally! What We’ve All Needed! Won’t Stay in Stock…

cheapaudioman

P4 is a home‑run preamp, combining quality and utility.

Old Guy Hifi

Practical review: P4 integrates neatly into entry‑level Hi‑Fi.

Matt Coykendall

Deep dive: P4 + V3 Mono synergy explained.

Pieces of Vinyl

Comparative test: do you really need the P4 preamp?

Mad Audio

Is P4 the best budget analog preamp available?

Techder Audios

Finally! What We’ve All Needed! Won’t Stay in Stock…

cheapaudioman

P4 is a home‑run preamp, combining quality and utility.

Old Guy Hifi

Practical review: P4 integrates neatly into entry‑level Hi‑Fi.

Matt Coykendall

Deep dive: P4 + V3 Mono synergy explained.

Pieces of Vinyl

Comparative test: do you really need the P4 preamp?

Mad Audio

Is P4 the best budget analog preamp available?

Techder Audios

Another Masterpiece Driven by Voice of Customers

The P4 is a mini preamp self-developed by Fosi Audio based on extensive feedback from users worldwide after the launch of the V3 stereo amp.

Input: RCA x3; Output: RCA, Pre-Out
SNR≥ 110dB; THD+N≤ 0.003%
Frequency Response: 20Hz-20kHz(±0.1dB)

High-Precision Motorized Analog Pot

Offer smooth volume adjustment while reducing noise and distortion for a purer soundscape.

Pre-Out Port

Expandable connection for powered subwoofers/powered speakers.

3-Level Gain Adjustment

Match different output levels from audio sources for improved sound quality.

Tone Control Bypass

Bypass the tone control circuit to enjoy the purest high-fidelity sound.

Enjoying a Convenient Audio Experience

Easily adjust the volume, switch sources, and control the tone without leaving your seat.

P4 & ZP3 Comparison

Thinking about a new preamp? Let’s line up P4 and ZP3, and see what makes each one special.

Product details

Description

Mini Control Hub: The P4 supports up to 3 RCA inputs, allowing easy connection to CD players, streamers, DACs, cassette decks, and turntables with built-in phono preamp. Switch between sources with a click for seamless audio control.
Practical and User-Friendly: Equipped with volume control, bass and treble adjustment with bypass function, three-level gain control, and a remote. The preamplifier offers convenient audio setup and optimization, making every listening session effortless.
Motorized Potentiometer: Featuring a high-precision motorized analog pot, the P4 delivers smooth volume adjustment, reduced noise, and minimal distortion for a purer and more refined sound experience.
Compact and Solid: The P4 stereo preamp features a sleek, minimalist design that saves space and provides robust resistance to electromagnetic interference, ensuring reliable performance over time.
Exceptional Performance: With a low noise floor, high signal-to-noise ratio, and extremely low distortion, the P4 pre-amplifier delivers pristine audio, ensuring accurate sound reproduction and enhancing the listening experience for audiophiles

Specifications

Channel: 2.0
Input Mode: RCA*3
Output Mode: RCA, Pre-out
SNR: ≥ 110dB
Dynamic Range: ≥ 110dB
THD+N: ≤ 0.003%
Crosstalk: ≥ 105dB
Noise Floor: ≤ 9μV
Tone Adjustment Gain: ±12dB
Frequency Response: 20Hz-20kHz(±0.1dB)
Power Supply: DC 12V/1.5A

What‘s in the box？

Fosi Audio P4 Mini Preamplifier x 1
12V/1.5A Power Supply x 1
User’s Manual x 1

Which Product is right for you?

Compare products to find the best one for your needs.

From $199.99

Fosi Audio ZP3 Preamplifier

Learn more

Type

Preamp

Input

RCA x2, XLR

Output

RCA, XLR, Sub-Out

Bass & Treble Control

Yes

THD+N

≤ 0.0007%

SNR

≥ 115 dB

From $99.99

Fosi Audio P4 Mini Preamplifier

Learn more

Type

Preamp

Input

RCA x3

Output

RCA, Pre-Out

Bass & Treble Control

Yes

THD+N

≤ 0.003%

SNR

≥110dB

From $79.99

Fosi Audio P3 Tube Preamplifier

Learn more

Type

Preamp+Headphone Amp

Input

Bluetooth, RCA

Output

RCA, 3.5mm Headphone Jack, AUX

Bass & Treble Control

Yes

THD+N

≤0.02%

SNR

≥103dB

From $199.99

Fosi Audio ZP3 Preamplifier

Learn more

Type

Preamp

Input

RCA x2, XLR

Output

RCA, XLR, Sub-Out

Bass & Treble Control

Yes

THD+N

≤ 0.0007%

SNR

≥ 115 dB

From $99.99

Fosi Audio P4 Mini Preamplifier

Learn more

Type

Preamp

Input

RCA x3

Output

RCA, Pre-Out

Bass & Treble Control

Yes

THD+N

≤ 0.003%

SNR

≥110dB

From $79.99

Fosi Audio P3 Tube Preamplifier

Learn more

Type

Preamp+Headphone Amp

Input

Bluetooth, RCA

Output

RCA, 3.5mm Headphone Jack, AUX

Bass & Treble Control

Yes

THD+N

≤0.02%

SNR

≥103dB

5 stars: 157 (89%)
4 stars: 16 (9%)
3 stars: 3 (2%)
2 stars: 0 (0%)
1 star: 0 (0%)

Beats everything the influencers are plugging as upgrades

I'm not sure why the review ecosystem got down on this particular model but, for whatever reason, those guys owe me a LOT of wasted upgrade money. I tried it against a ZP3, a Fiio K13, a GR40 and an MC331, and it CLOBBERS all of them for sound. It's just that simple. Absolutely sensational sound at any price; literally gob-smacking at the entry point it has. Buy one right this second.

Gets the job done!

Finally this pre amp completes my setup. Now I can easily switch between analog audio from my SB AE5+, tv via optical thru Q6, and streamer using echo show 1st Gen. Im quite satisfied with this.

You can never go wrong with FOSI

its been a breeze owning the p4 mini !!!

깔끔하고 편해서 좋습니다.

여러 입력소스를 셀렉터 변경으로 사용중
P4로 구입후 변경하였는 데
리모컨 사용도 할 수 있어 정말 편하고 안정적입니다.

An amazing device, connected to different amplifiers, I can say it's quite smooth and very dynamic. For those who lack dynamics and drive in their acoustics, get it, you won't regret it!!!

Excellent device

I connected two mono v3 outputs to an E 50 DAC topping, used as a preamp, and the reproduced sound was already very good in the bass, a bit less in the mid and high ranges. I have decided to purchase the pre P4, more so to have control over the tones, as well as the knobs, given that the pre-dac topping e 50 only has volume control on the remote. As I expected with this preamp P4 connected to the DAC and the two outputs, the sound has significantly improved, especially in the mid-high range and also in terms of volume. I also ordered two Oracle 2 op-amps to replace the originals and I believe I will have further improvement. I recommend the purchase, I got it on promotion for 87 euros, what can I say, unbeatable value for money.

The fosi p4 preamplifier is a great value. It handles multiple inputs and produces transparent and well articulated sound.

Great little device.

I love this little preamp from Fosi. I use it as a desktop device, next to an Xduoo tube headphone amp, an SMSL DAC, and AIYIMA A07 Max power amp. I like the design, and the simplicity of use, it is easy to replace the op-amp in it, but... Those buttons are hard to take off...

Small objects of desire

After watching countless reviews I felt like I was back in the seventies again, when I had to assemble my first basic stereo set from different components like a sony 212 amp, philips ah489 speakers and an akai turntable. It didn’t only look great, it had a great sound too, at least to me. I truly felt like a junior audiophile.

Fast forward to today and again I had the same fun experience, even though the components were all of the same brand, I still had a lot of flexibility, In my case I went for V3 mono’s, because I was actually contemplating buying full fledged units, but Fosi gave me the opportunity to try out such a system (2xv3 mono, zd3 dac and a p4 preamp) without braking the bank.

Not only does it all look and feel absolutely great, it also sounds very good, and I haven’t even tried rolling op amps yet. I also recently bought a fosi phono tube preamp for a vintage technics sl2000, which absolutely enhanced the sound audible and exponentially, and that for a ridiculously low price of €50,- (special offer). It actually made me wonder how they still make a profit.

No regrets here!

Pretty impressive little thing …

I‘ve added a P4 Mini to my system recently and it benefits a lot in therms of sound clarity, details and imaging. I am pretty happy with this purchase.

I ordered the perfect combo phono preamp box x5 and 3rca p4 preamp for my project x1 turntable. The p4 allows some bass and treble adjustment according to poorly pressed vinyl, but this is rarely needed.

I bought it to use in the car and got caught between DAP and DSP. The music has more power and the background becomes clearer. It suits beginner or intermediate systems, and I ordered to replace it with muses02 opamp, but now I have to wait again for the replacement.

Excellent desktop Pre-Amp!

I really like the sound quality of this desktop mini Pre-amp, I swapped the op amp with a Burson V7 vivid and it sounds even better, to my ears. Besides its great sound, this unit has tone controls and three RCA inputs, and in addition to the RCA output, there's a 3.5 mm pre out that I use to connect my GR70 headphone amp. Five stars for Fosi Audio, again!

I have received it well. The sound quality is high and good.

Great product, very well constructed.

The sound quality is good. There are various options such as bypass and gain adjustment functions, and it will get even better with aging.

Great preamplifier with remote control, very high-quality workmanship, I find the bypass function very good. Treble and Bass controls lock in neutral position. Unfortunately not the same width as the V3 Monos.

Excellent product and fast delivery directly from Brazilian stock. I managed to connect them in a pair of Edifier boxes, adding more RCA inputs to them and also a subwoofer output.

Посылка доставлена!

Большое спасибо.
Доставили очень быстро.
Предусилитель просто супер.

Very high-quality preamplifier, I recommend it.

Il tuo carrello è vuoto.

Fosi Audio P4 Mini Preamplifier

Review Videos

Finally! What We’ve All Needed! Won’t Stay in Stock…

P4 is a home‑run preamp, combining quality and utility.

Practical review: P4 integrates neatly into entry‑level Hi‑Fi.

Deep dive: P4 + V3 Mono synergy explained.

Comparative test: do you really need the P4 preamp?

Is P4 the best budget analog preamp available?

Finally! What We’ve All Needed! Won’t Stay in Stock…

P4 is a home‑run preamp, combining quality and utility.

Practical review: P4 integrates neatly into entry‑level Hi‑Fi.

Deep dive: P4 + V3 Mono synergy explained.

Comparative test: do you really need the P4 preamp?

Is P4 the best budget analog preamp available?

Fosi Audio P4 Mini HiFi Preamplifier

Another Masterpiece Driven by Voice of Customers

High-Precision Motorized Analog Pot

Pre-Out Port

3-Level Gain Adjustment

Tone Control Bypass

Enjoying a Convenient Audio Experience

P4 & ZP3 Comparison

Product details

Which Product is right for you?

Fosi Audio ZP3 Preamplifier

Fosi Audio P4 Mini Preamplifier

Fosi Audio P3 Tube Preamplifier

Fosi Audio ZP3 Preamplifier

Fosi Audio P4 Mini Preamplifier

Fosi Audio P3 Tube Preamplifier

FAQs

Customer Reviews

Fosi Audio P4 Mini Preamplifier

Review Videos

Finally! What We’ve All Needed! Won’t Stay in Stock…

P4 is a home‑run preamp, combining quality and utility.

Practical review: P4 integrates neatly into entry‑level Hi‑Fi.

Deep dive: P4 + V3 Mono synergy explained.

Comparative test: do you really need the P4 preamp?

Is P4 the best budget analog preamp available?

Finally! What We’ve All Needed! Won’t Stay in Stock…

P4 is a home‑run preamp, combining quality and utility.

Practical review: P4 integrates neatly into entry‑level Hi‑Fi.

Deep dive: P4 + V3 Mono synergy explained.

Comparative test: do you really need the P4 preamp?

Is P4 the best budget analog preamp available?

Fosi Audio P4 Mini HiFi Preamplifier

Another Masterpiece Driven by Voice of Customers

High-Precision Motorized Analog Pot

Pre-Out Port

3-Level Gain Adjustment

Tone Control Bypass

Enjoying a Convenient Audio Experience

P4 & ZP3 Comparison

Product details

Which Product is right for you?

Fosi Audio ZP3 Preamplifier

Fosi Audio P4 Mini Preamplifier

Fosi Audio P3 Tube Preamplifier

Fosi Audio ZP3 Preamplifier

Fosi Audio P4 Mini Preamplifier

Fosi Audio P3 Tube Preamplifier

FAQs

Customer Reviews

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