---
product_id: 107404737
title: "Fosi Audio BOX X4 Phono Preamp Headphone Amplifier/Preamplifier Hi-Fi Pre Amp with JAN 5725W Vacuum Tubes for MM Turntable Phonograph Record Player with Volume Bass Treble Control"
brand: "fosi audio"
price: "€ 227.19"
currency: EUR
in_stock: true
reviews_count: 8
category: "Fosi Audio"
url: https://www.desertcart.fi/products/107404737-fosi-audio-box-x4-phono-preamp-headphone-amplifier-preamplifier-hi
store_origin: FI
region: Finland
---

# Customizable vacuum tube sound Dual RCA + headphone outputs Pro-grade MM phono stage Fosi Audio BOX X4 Phono Preamp Headphone Amplifier/Preamplifier Hi-Fi Pre Amp with JAN 5725W Vacuum Tubes for MM Turntable Phonograph Record Player with Volume Bass Treble Control

**Brand:** fosi audio
**Price:** € 227.19
**Availability:** ✅ In Stock

## Summary

> 🎶 Elevate your vinyl game—hear what you’ve been missing!

## Quick Answers

- **What is this?** Fosi Audio BOX X4 Phono Preamp Headphone Amplifier/Preamplifier Hi-Fi Pre Amp with JAN 5725W Vacuum Tubes for MM Turntable Phonograph Record Player with Volume Bass Treble Control by fosi audio
- **How much does it cost?** € 227.19 with free shipping
- **Is it available?** Yes, in stock and ready to ship
- **Where can I buy it?** [www.desertcart.fi](https://www.desertcart.fi/products/107404737-fosi-audio-box-x4-phono-preamp-headphone-amplifier-preamplifier-hi)

## Best For

- fosi audio enthusiasts

## Why This Product

- Trusted fosi audio brand quality
- Free international shipping included
- Worldwide delivery with tracking
- 15-day hassle-free returns

## Key Features

- • **Tailor Your Tone:** Active ±10dB bass and treble controls let you sculpt warmth or crispness to match your vinyl’s vibe.
- • **Tube Rolling Freedom:** Swap tubes like a pro to unlock unique sound signatures and personalize your listening experience.
- • **Plug & Play Confidence:** Complete kit with power supply, manual, and 24-month warranty ensures worry-free setup and support.
- • **Audiophile-Grade Clarity:** Experience pristine analog sound with low-noise JAN 5725W vacuum tubes and grounding terminal to eliminate hum.
- • **Seamless Listening Modes:** Switch effortlessly between RCA line-level output and headphone amp for private or shared vinyl sessions.

## Overview

The Fosi Audio BOX X4 is a compact, high-fidelity phono preamp and headphone amplifier designed for MM turntables. Featuring premium JAN 5725W vacuum tubes, dual RCA and headphone outputs, and adjustable bass/treble controls, it delivers crystal-clear analog sound with customizable tonal options. Its grounding terminal eliminates hum, while tube rolling flexibility invites audiophiles to tailor their sound. Perfect for late-night listening or enhancing any vinyl setup, it comes with a full kit and 24-month warranty for peace of mind.

## Description

Fosi Audio BOX X4 Phono Preamp Headphone Amplifier/Preamplifier Hi-Fi Pre Amp with JAN 5725W Vacuum Tubes for MM Turntable Phonograph Record Player with Volume Bass Treble Control : desertcart.co.uk: Electronics & Photo

Review: Packs a punch for the price point and sounds cosmic! - Straight out the box, you can tell this is value for money. Nice size, with the much needed base and treble on the front included with the volume control. As others have said, getting the vaccum valves in can be a fiddle, but just take your time and give them a wiggle on a way in, you'll know when you've got them straight. Easy RCA connections on the rear, with the earth plug, which is neat as you can just put in a stripped cable and lock it off with one press, nice and easy. This is perfect for my PL112-D as it immediatly eliminates any hum. Straight off the bat, tried out some James Taylor and wow, what a difference this amp has made to my old amp. The clarity is quite something. Like other reviews have said, you can just "hear more" of the sound stage, its quite remarkable. Slight tweaks of the treble and bass bring more clarity. Really nice sound. Onto something a little heavier, some AC/DC and bam, the sound is thumping, again very clear and much, much better than my old amp which was around the same price. Just to note, I initially experienced some issues with the amp, but customer service were amazing. For transparency, the issue wasn't the amp, it was the RCA cables that needed changing over. I did this, along with a brand new set of tone arm cables and wow, it sounds even better! For the price, I honestly can say, it's perfect. It really does make the sound better, smoother and it's going through a main amp, with further settings for clear, soft, heavy and neutrel. I've just left that on clear and only used the treble and base on this pre-amp for playing tracks. Very, vey pleased with the product, would not hesitate to recommend this. My table is a 1970's Pioneer PL112-D and whilst it's only a very low end entry level table, it fits my needs and sounds brand new with this pre-amp. Many comments from friends and family on the clarity and smooth sound. Can't be any fairer than that! So, if you are in the mood for a well priced, tidy, smooth sounding amp with great customer service from the manufacturer then dive in, I don't think you will regret it.
Review: Better than my Rega - I have an ok enough system, a Sony ps-lx310bt, paired with some wharfedale Denton 80th anniversary speakers and an older onkyo tx-sr307. Before now I was using a used rega fono a2d mkii. I was happy with the rega and it comes highly rated. However, when I treated myself to the dentons I wanted to see if I could get a little more out from the system. My amp is next to upgrade but this little preamp being so cheap, I thought it worth the gamble. I can absolutely tell you now that this works and it’s a better preamp than my Rega. The best way I can describe it is that I could hear separate instruments with the rega but they were almost all waiting their turn and you could only hear say, a guitar, in between any trumpet bits or vice versa. Now, with this Fosi, I hear ALL the instruments, ALL the time. It’s a huge cliche but I’m hearing things in songs that I didn’t know were there previously. My fosi has about 80 or so hours in it now so should be burnt in enough and there is a difference between hour 1 and hour 80 with the first hours being a little harsh/bright. There’s a lovely softness now to the highs and piano sounds are so much more succinct and if you closed your eyes you could almost place one in the room. Bass is, at worst; just as tight as the rega, probably a tad more so. I do use a wharfedale SW150 sub and have no need for more. The Bluetooth function works brilliantly. I only pair with my iPhone and listen to Tidal and can quite honestly say I have no desire for an external dac at the moment. The unit is dead quiet. No hum, no buzz, no interference. It’s quieter than my rega and that costs £100 and gets 5 stars on “What-Hifi”. There is snobbery in the audiophile world and I’m totally sure if this was rebranded as a Rega or Schiit that it would be getting a lot more attention. I bought some decent QED profile rca leads from desertcart and a similar quality aux input for my receiver (an Aukey receiver with Bluetooth 5) and I’m pretty set. I did upgrade my stylus to an LP Gear which outputs 2.5mV so set my gain to 42 decibels accordingly. And yes, this amp is also louder than my rega, not that this means anything to your amp but previous to this, I was at about 55 for volume and now 40 is sometimes too loud depending on the song. All this with no distortion at any volume I’ve tried. Honestly, if you’re on the fence, get down. Buy this and if you don’t get on, you’ve got desertcart’s return policy. I did also get the GE5654 tubes and have used them since day 1 so can’t comment on the ones that came with but I have them as spare if I need them. My friend has the project ds2 which cost him about £400 and I’m not saying this sounds the same but there’s definitely not a £340 difference between the two. And finally, yes the tubes are real and not used as a buffer as there is a slight delay on startup as the bulbs warm up.

## Features

- Pro-Grade MM Phono Stage with Grounding Terminal: Upgraded from BOX X2, the BOX X4 delivers audiophile-grade clarity for your turntable. Features a low-noise JAN 5725W vacuum tube preamp with MM input and built-in earth terminal to eliminate hum and protect vinyl systems. Ensure your turntable’s internal preamp is disabled for pure analog playback.
- Dual-Output Flexibility--Preamp + Headphone Amp：Switch seamlessly between RCA line-level output for amplifiers and 3.5mm headphone output for private listening. Engineered to drive most headphones, ideal for late-night vinyl sessions without disturbing others.
- Tube Rolling Flexibility for Custom Sound：Unlock endless audio personalities! Swap stock JAN 5725W tubes with 6K4/6J1/GE5654/6AK5 tubes (sold separately). A DIY haven for vinyl enthusiasts.
- Active Bass & Treble Controls for Vinyl Optimization：Fine-tune your records with ±10dB bass/treble EQ – boost warmth for vintage LPs or sharpen detail for modern pressings. Paired with low-noise circuitry to preserve original analog character.
- Complete Kit with Extended Warranty：Includes BOX X4 phono preamp, DC 12V power supply, user manual, our worry-free 24-month warranty, and friendly customer service.

## Technical Specifications

| Specification | Value |
|---------------|-------|
| ASIN | B07L4TMHRN |
| Best Sellers Rank | 1,085 in Electronics & Photo ( See Top 100 in Electronics & Photo ) 1 in Home Audio Preamplifiers 1,446 in Hi-Fi & Home Audio Accessories |
| Item model number | BOX X4 |
| Manufacturer | Fosi Audio |
| Product Dimensions | 10.16 x 5.08 x 2.54 cm; 362.87 g |

## Product Details

- **Item dimensions L x W x H:** 10.2 x 5.1 x 2.5 centimetres
- **Manufacturer:** Fosi Audio
- **Maximum supply voltage:** 12 Volts (DC)
- **Minimum supply voltage:** 12 Volts (DC)
- **Voltage:** 12 Volts (DC)

## Images

![Fosi Audio BOX X4 Phono Preamp Headphone Amplifier/Preamplifier Hi-Fi Pre Amp with JAN 5725W Vacuum Tubes for MM Turntable Phonograph Record Player with Volume Bass Treble Control - Image 1](https://m.media-amazon.com/images/I/61W0YonYLBL.jpg)

## Questions & Answers

**Q: I have the pyle turntable and fosi audio tb10a amp but the sound is very low, so i need to add this phono preamp to amplify sound?**
A: Yes, you need connect this phono preamp between the turntable and tb10a amp, it will amplify the sound also improve the sound quality.
Thanks.

**Q: Can I directly connect this phono preamp to the speakers?**
A: If your speakers are powered speakers, you can directly connect this preamp to the speakers. 
But you need add an amplifier or receiver to the passive speakers.
Thanks.

**Q: Does this work best with Ceramic or Magnetic stylii? Can it do both?**
A: As long as your cartridge can output a voltage between ~2.0 -5 0 millivolts, the Fosi Audio Box X4 should work.  Amazon cells ceramic cartridges around $10, that I want to experiment with one.  Thanks for your question.

**Q: Why would an upgraded model have an snr of 70db and the older version is at 98db? seems like a downgrade. are those specs correct?**
A: I have a feeling that either this measurement is incorrect or the previous model's measurement is wrong. There is not enough information in either measurement; how did they do it? What kind of signal was used? What frequency? Was this measured with or without a signal going into it? Was it measured while playing an actual track off vinyl, or dead wax? Did the SNR change if you engaged the EQ? 

Even if the previous model gave you 98dB, it's impossible to reach that measurement with vinyl — even the cleanest, best vinyl ever made while using the most expensive, best stylus, cartridge, preamp, etc. isn't going to give you anything better than ~70dB. The X4 specs state ≥ 70dB which means at the very least it will give you 70dB or above. 

Having said all that, I think the X4 sounds great, especially for the price!

## Customer Reviews

### ⭐⭐⭐⭐⭐ Packs a punch for the price point and sounds cosmic!
*by M***T on 16 July 2025*

Straight out the box, you can tell this is value for money. Nice size, with the much needed base and treble on the front included with the volume control. As others have said, getting the vaccum valves in can be a fiddle, but just take your time and give them a wiggle on a way in, you'll know when you've got them straight. Easy RCA connections on the rear, with the earth plug, which is neat as you can just put in a stripped cable and lock it off with one press, nice and easy. This is perfect for my PL112-D as it immediatly eliminates any hum. Straight off the bat, tried out some James Taylor and wow, what a difference this amp has made to my old amp. The clarity is quite something. Like other reviews have said, you can just "hear more" of the sound stage, its quite remarkable. Slight tweaks of the treble and bass bring more clarity. Really nice sound. Onto something a little heavier, some AC/DC and bam, the sound is thumping, again very clear and much, much better than my old amp which was around the same price. Just to note, I initially experienced some issues with the amp, but customer service were amazing. For transparency, the issue wasn't the amp, it was the RCA cables that needed changing over. I did this, along with a brand new set of tone arm cables and wow, it sounds even better! For the price, I honestly can say, it's perfect. It really does make the sound better, smoother and it's going through a main amp, with further settings for clear, soft, heavy and neutrel. I've just left that on clear and only used the treble and base on this pre-amp for playing tracks. Very, vey pleased with the product, would not hesitate to recommend this. My table is a 1970's Pioneer PL112-D and whilst it's only a very low end entry level table, it fits my needs and sounds brand new with this pre-amp. Many comments from friends and family on the clarity and smooth sound. Can't be any fairer than that! So, if you are in the mood for a well priced, tidy, smooth sounding amp with great customer service from the manufacturer then dive in, I don't think you will regret it.

### ⭐⭐⭐⭐⭐ Better than my Rega
*by R***R on 17 January 2021*

I have an ok enough system, a Sony ps-lx310bt, paired with some wharfedale Denton 80th anniversary speakers and an older onkyo tx-sr307. Before now I was using a used rega fono a2d mkii. I was happy with the rega and it comes highly rated. However, when I treated myself to the dentons I wanted to see if I could get a little more out from the system. My amp is next to upgrade but this little preamp being so cheap, I thought it worth the gamble. I can absolutely tell you now that this works and it’s a better preamp than my Rega. The best way I can describe it is that I could hear separate instruments with the rega but they were almost all waiting their turn and you could only hear say, a guitar, in between any trumpet bits or vice versa. Now, with this Fosi, I hear ALL the instruments, ALL the time. It’s a huge cliche but I’m hearing things in songs that I didn’t know were there previously. My fosi has about 80 or so hours in it now so should be burnt in enough and there is a difference between hour 1 and hour 80 with the first hours being a little harsh/bright. There’s a lovely softness now to the highs and piano sounds are so much more succinct and if you closed your eyes you could almost place one in the room. Bass is, at worst; just as tight as the rega, probably a tad more so. I do use a wharfedale SW150 sub and have no need for more. The Bluetooth function works brilliantly. I only pair with my iPhone and listen to Tidal and can quite honestly say I have no desire for an external dac at the moment. The unit is dead quiet. No hum, no buzz, no interference. It’s quieter than my rega and that costs £100 and gets 5 stars on “What-Hifi”. There is snobbery in the audiophile world and I’m totally sure if this was rebranded as a Rega or Schiit that it would be getting a lot more attention. I bought some decent QED profile rca leads from Amazon and a similar quality aux input for my receiver (an Aukey receiver with Bluetooth 5) and I’m pretty set. I did upgrade my stylus to an LP Gear which outputs 2.5mV so set my gain to 42 decibels accordingly. And yes, this amp is also louder than my rega, not that this means anything to your amp but previous to this, I was at about 55 for volume and now 40 is sometimes too loud depending on the song. All this with no distortion at any volume I’ve tried. Honestly, if you’re on the fence, get down. Buy this and if you don’t get on, you’ve got Amazon’s return policy. I did also get the GE5654 tubes and have used them since day 1 so can’t comment on the ones that came with but I have them as spare if I need them. My friend has the project ds2 which cost him about £400 and I’m not saying this sounds the same but there’s definitely not a £340 difference between the two. And finally, yes the tubes are real and not used as a buffer as there is a slight delay on startup as the bulbs warm up.

### ⭐⭐⭐⭐⭐ A marked improvement on my turntable’ built in preamp.
*by J***N on 4 June 2024*

The unit seems to be well made. The Valves were unbranded but seem to work well and were easy to install (I might try some upgrades at some point but don’t think it is necessarily going to make much difference). I am using it as a preamp for a Sony PS-LX310BT which I am running through some Edifier active speakers in my home office (one of the perks of working from home). The improvement to the sound was marked and the volume and tone controls work well (I am using the bass and treble controls as the primary tone controls and leaving the Edifier tone controls as neutral). I have found that the volume is best set fairly high on the Box X3 to get the full effect of the valves and the Edifier volume control used as the primary. The valves give a warm sound characteristic but not at the expense of clarity. The overall sound is very clear. Great value for money at £72. Can’t speak for its longevity as I have only had it a couple of days but would say that I am very impressed so far.

## Frequently Bought Together

- Fosi Audio Box X4 Phono Preamp with JAN 5725W Vacuum Tubes for MM Turntable Phonograph Record Player with Volume Bass Treble Control
- Monoprice 1.5ft Premium 2 RCA Plug/2 RCA Plug M/M 22AWG Cable - Black
- Riverstone Audio - Tested/Matched Pair (2 Tubes) 7-Pin JAN 5654W Fully-Tested Vacuum Tubes - Upgrade for 6AK5 / 6J1 / 6J1P / EF95 - JAN 5654W Platinum Grade Pair

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*Product available on Desertcart Finland*
*Store origin: FI*
*Last updated: 2026-02-06*