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Fosi Audio

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

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Availability: 20 left in stock
Fulfilled by Amazon
Arrives Tuesday, Oct 20
Order within 18 hours and 46 minutes
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Features

  • 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 pre amp 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

Description

Equipped with triple inputs, tone control, and remote control for a convenient and customizable audio experience. 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. Easily connect up to three audio sources, with one-touch input switching for ultimate audio freedom. With a harmonious appearance, it elevates both the visual and audio experience of your sound system. Metallic texture, compact and refined, with enhanced resistance to electromagnetic interference. Achieve personalized sound signature for a tailored listening experience. Match different output levels from audio sources for improved sound quality. Bypass the tone control circuit to enjoy the purest high-fidelity sound. Easily adjust the volume, switch sources, and control the tone without leaving your seat. Offer smooth volume adjustment while reducing noise and distortion for a purer soundscape. Expandable connection for powered subwoofers/powered speakers. 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. Does P4 support multiple RCA inputs playing together? No, P4 only supports one input channel at a time. P4 ZD3 ZP3 ZH3 ZA3 Q6 BOX X5

Item dimensions L x W x H: 5.5 x 4 x 1.2 inches


Manufacturer: Shenzhen Foresight Technology Co., Ltd.


Mounting Type: Freestanding


Brand: Fosi Audio


Number of Channels: 2


Mounting Type: Freestanding


Number of Channels: 2


Item Dimensions: 5.5 x 4 x 1.2 inches


Manufacturer: Shenzhen Foresight Technology Co., Ltd.


Model: P4


Brand Name: Fosi Audio


Number of Items: 20


Warranty Description: 24-month Manufacturer


Unit Count: 1 Count


Included Components: Fosi Audio P4 Preamplifier x1, User Manual x1, Remote Control x1, 12V/1.5A Power Supply x1


Item Weight: 477 g


Part Number: P4


Frequently asked questions

If you place your order now, the estimated arrival date for this product is: Tuesday, Oct 20

Yes, absolutely! You may return this product for a full refund within 30 days of receiving it.

To initiate a return, please visit our Returns Center.

View our full returns policy here.

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Top Amazon Reviews

    • This is an upgrade just what I was looking for for my extreme ultimate custom surround sound system
Review Image by Thomas E Soundmaster
Review Image by Thomas E Soundmaster
Review Image by Thomas E Soundmaster
Review Image by Thomas E Soundmaster
Review Image by Thomas E Soundmaster
Review Image by Thomas E Soundmaster
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Review Image by Thomas E Soundmaster
Review Image by Thomas E Soundmaster
Well okay this preamp here by Fosi audio is an upgrade from what I did have and trust me I like them both no I love them both the sabaj is a headphone line preamp but it doesn't have a base or trouble feature on it it has a remote is the reason why I bought it for the sound system that I was creating but I currently can't get that one no more so I was trying to find another one just in case that one went out which was that one still works I have two of those type but I was looking for one more I stumbled across this one by fosi audio and this is a great upgrade cuz it's got the features that I was looking for Bass and trouble and it also has instead of one line in and one line out it's got three lines in and one line out but it also has a gain control switch a bypass control switch in the back a knob to turn it up and down manually and with the remote control the knob is powered and you can control the three line channels and it stays in sync whatever Channel you switch to that's a pretty cool feature and the best feature of all that I think well one of the best is you don't have to point the remote directly at the Box you could be off or you can pull it towards the wall or you can be halfway up in the air and the signal still will connect for turning it up and down or switching it but pointing Straight Ahead towards the boxes fine but it still picks up the signal even if you do not directly towards the Box and that's a great feature I've been looking for something like that the other one I had on there you had to be directly pointed towards the preamp and if you wasn't close enough It wouldn't connect but this one connects great I'm going to buy another one of these and they got to upgrade one a much more professional one I believe will be great for the system the professional one I will change with this one and put the more higher Advanced one on to make the system complete which the system is already complete but I've been adding on other items to it this got great sound it's much much more than a ultimate surround sound system it is also a system that you can use for music and it also has a recording feature on it that you can record with not only that when it comes down to movie night the movies are in Dolby Atmos because there's High speakers on the top and bottom and the base is outstanding this is one system that is a beast and this preamp that I have just bought with the base control in trouble has made it complete I recommend this preamp and other items that they have I look through the features that they are making and they got a lot of goodies lot of toys that I like to play with so definitely for $99 this upgrade is worth it and they got some more items that's right up my alley and the prices are not too high just right that will make this system even better or any other system that I'm creating or even you create check it out go out and buy give it a try I guarantee you will be happy and you will love it just the way I love it items like this helps you create custom systems and I hope they don't stop making them especially ones from this brand you doing a great job keep up the good work I'm going to look through their items again and figure out something else that might catch my eyes but the preamps definitely are a must and I will be purchasing things another one of these and something different very soon well that's it for me I'm out of here later ... show more
Reviewed in the United States on February 12, 2026 by Thomas E Soundmaster
    • More than decent for the price.
I love the features - 3 inputs, remote control for selecting input as well as motorized volume knob control, adjustments for bass and treble with ability to bypass the tone controls, 3 gain settings, nicely built. They really thought of everything. Definitely can't complain for $99. Is it 100% transparent? No. But it's quite, quite good. I did some tests with it with gear at different levels (compared with the P4 in the chain and not in the chain) and it's pretty transparent with entry to lower-mid level gear. As you step up to higher end gear, it becomes more apparent between when the P4 is or is not in the chain, as would be expected with a $99 device. But for my use case, I'm not putting it between 2 high end pieces. I still have my higher end pieces connected directly but am mainly using the P4 to connect multiple different inputs (DAC, streamer, phono pre-amp) from higher end pieces to a more entry/mid level tube headphone amp that I had to remove the potentiometer from and it's perfect for this. ... show more
Reviewed in the United States on February 19, 2026 by Keith S
    • Excellent addition for my needs....
Pairs seamlessly with and exceeded my expectations with my Fosi GR70 tube headphone amplifier. I didn't think the remote was necessary for the preamp but have found it to be so convenient that I'd try to purchase another if it failed. I don't hear anything but what the track pushes through it in the way of noise or distortion in my headphones. It has also allowed me to cut back on the GR70's volume knob placement to approximately the 2 o'clock (at most) position with the preamp volume setting at 1 o'clock. The bass/treble control settings I like are between 12 and 1 o'clock on both devices. I'm using my iPad Air with Amazon Music, a Questyle m12i, the P4, and Gr70 with my headphones. The small footprint of these devices (including a iFi Zen Air Can for solid state listening when desired) allows me to enjoy all my playlists (classic rock, acoustic, jazz, solo artists, and other genres) while kicked back in my living room recliner. This setup delivers all the volume and audio quality I currently need considering my age related and lifestyle choices hearing losses. I'm very pleased with this purchase and addition to my budget (less than $500) living room "stereo system" excluding the two previously purchased headphones and iPad.... ... show more
Reviewed in the United States on November 9, 2025 by Ted...
    • A lot of bang for your money.
The Fosi Audio P4 Mini Preamp is a well made small and relatively inexpensive preamp featuring a 3-way 'Mode' switch on the far left of the front of the unit, then 3 dials, 'Bass', 'Volume' and 'Treble'. The Bass and Treble controls had an indent as you turn the dial to the 12 o'clock position, which I like. The center 'Volume' knob a metallic Orange in color. This matches with some of Fosi's other products. Finally there's a Infra-red sensor for the included remote control. On the back are 3 RCA inputs, right and left channel RCA outputs for your speakers, a 'Pre Out' that most people will probably use with a powered subwoofer, although there's no low pass filter feature to send only the lower frequency signals to a subwoofer. There's a 'Bypass' switch 'On' or 'Off' to bypass the tone controls located on the front of the unit. There's a 'Gain' switch with '3dB', '6'dB' and '9dB' settings. The default position the unit is shipped with is '6dB'. The '6dB' setting worked fine with my Fosi V3 amp and Infinity P163 speakers and didn't need much adjusting to get the right volume. Finally, there's a 'DC 12V' power socket. The remote is decently built. The only thing to be aware of is it works with several Fosi products and buttons on the front of the remote is how to set it to your P4 preamp. In use I didn't notice any degradation of the sound. Having the Bass and Treble controls is nice to help you tweak the sound. With the Fosi V3 I boosted the Bass just a hair. Depending on what I'm listening to I'll adjust the Treble to clarify dialog with TV shows and movies. I'm thinking of adding an equalizer in the future and bypassing the tone controls. My only gripe, hence the missing 5th star, is that I wish Fosi would standardize on the size and case design of their new products. As far as I can tell the Fosi P4 doesn't match the size and shape of any of their other products. They are missing an opportunity. Otherwise the P4 is definitely a 5 star product if judged by itself. The P4 replaced a $50 Schiit SYS 2-input preamp I bought just a couple months ago. If I'd known the Fosi P4 was coming I would have waited for it to gain the extra input, remote, Bass and Treble controls, and Pre-out. Even without the extra discount coupon the Fosi is worth it. I bought the P4 with my own money. I did take advantage of a big discount they offered to everyone when the unit was first available on Amazon. It took only one week day to arrive. I route my SMSL Su-1 DAC and Schiit Mani 2 phono preamp through the Fosi. My turntable is a Rega P1 with an upgraded Audio Technica AT-VM95EN cartridge which is a great sounding combo. ... show more
Reviewed in the United States on February 25, 2025 by Robert J.
    • Nice preamp, especially for this price
This is a very nice preamp if you to deliver clean audio to your amp and don't want to spend a ton of money needlessly. I bought this to sit between my DAC and my power amp, just to have a volume control separate from the DAC, and the added protection for my speakers. (The amp is almost too powerful.) This preamp introduces no noticeable noise or coloration to the sound, just provides a bit of gain and a volume control. The gain is adjustable (3/6/9dB): I'm using it at the lowest setting. There is a tone control, but there's also a switch to bypass it completely, which is what I did. For the price, this is ridiculously good. ... show more
Reviewed in the United States on April 4, 2026 by orangecat
    • Perfect
If you're like me and have a powered subwoofer and a nice amp to drive your magnepan speakers then this is the perfect preamp! I just got a good Bluetooth receiver and by that I mean ldac codec to receive lossless Spotify from my z-fold five. I've done records, I've done CDs, I've done my own personal lossless music collection... I've done countless AB tests switching from record to CD testing the different formats of MP3 to see when I stop noticing the difference. I've had a lot of fun doing all that. Right now I'm just seeing if I can tell the difference between the $100 blue dento DAC and the $50 Mii B06... Jury is still out. I will have to enlist my son who has better hearing than I do and is actually a musician also so he probably has a more discerning ear to add to the discussion. I'm still not sure if the dento has the burr brown codec, but I think the B06 has the ESS (or something those rabbit holes are interesting but now I'm just going for what I can hear and what I like) oh so I guess that's what I was getting to, at this point I just want to enjoy the music and know that I'm pretty close to good enough. Anyone who's gone down this rabbit hole nose you end up realizing that your room is probably the most important part of your setup and you're not going to start making it look like a music studio... And the best sound I've ever heard has come from headphones anyway. Just make it as easy as possible to enjoy the music you have the time to put a record on and sit in The Sweet spot and enjoy it then do that too. Just be happy music is such a wonderful thing to enjoy 😁 ... show more
Reviewed in the United States on May 9, 2026 by Riverview
    • Nice sounding simple old-school preamp
I am using this for a secondary system, and it acts as a good sounding hub connecting a DAC, amp, and streamer, and monitor in an easy-to-use setup. I really like the remote control that lets you switch between inputs and motorized volume control. Plus, I have a small, powered subwoofer connected to the 3.5mm pre-out on the preamp. This is hard to beat for the money. ... show more
Reviewed in the United States on September 14, 2026 by Amazon Customer
    • Great pre amp!
I paired this with my Fosi ZA3 and it literally rocks! I have it paired up with Klipsch R6-600M and it literally sounds amazing!
Reviewed in the United States on July 28, 2026 by Gta

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