

🎶 Elevate your vinyl game with tube-powered precision!
The Fosi Audio Box X4 is a compact, next-generation phono preamp and headphone amplifier featuring replaceable JAN 5654W vacuum tubes for customizable sound. It supports both 3.5mm AUX headphone and RCA outputs, delivering versatile connectivity and high-fidelity audio tailored for MM turntables. Designed for audiophiles seeking premium tube warmth and control, it includes bass, treble, and volume adjustments, backed by a 24-month warranty and responsive customer service.














| ASIN | B07L4TMHRN |
| Best Sellers Rank | #24,403 in Electronics ( See Top 100 in Electronics ) #3 in Home Audio Phono Preamplifiers |
| Item model number | BOX X4 |
| Manufacturer | Fosi Audio |
| Product Dimensions | 10.16 x 5.08 x 2.54 cm; 362.87 g |
A**.
Nice product
Nice product
A**D
Bad
It’s so bad makes the sound quality disastrous
I**N
Just what I was looking for. I have an MM phono turntable (not amplified) and wanted to listen to vinyls with my headphones. The product has a solid feel with smooth controls. The volume, treble and bass controls really help. Good value.
B**F
I needed a preamp because I couldn't do what I wanted with my existing setup. I had Fluance RT-85 turntable > Onkyo TX-SV575 (25 years old) > Rockville 21-band graphic EQ via Tape 2 monitor > Wharfdale Diamond 7.2 bookshelf speakers (also 25 years old). This setup sounded great, but I also want to have the music play in other rooms in perfect synchronization. I use the Wiim streaming device for this. The issue is that with that is that the sounds lagged a noticeable few milliseconds in the other rooms. The Wiim synch feature didn't work because the source setup didn't have the signal come from the Wiim. I need to change the order of the signal chain so that the turntable signal passed through the Wiim then to the receiver. And that's why I needed a pre-amp. After a night of researching solid state and tube preamps, I decided on the Fosi Box X4. I ordered it after 3am and it arrived before 6pm that same day (nice job, Amazon!). Set up was easy. The only odd thing was that the grounding post on the X4 is spring-loaded mechanism that seems intended for bare wire or a pin rather than the spade connector that is common on turntables. So I fed one prong of th fork into the opening and that works fine. The chain is now turntable > preamp > EQ > Wiim > receiver. This works but the sound seemed a little off. especially on older records. If I spent more time adjusting the EQ, I could probably get the sound to where I want it, but I'm lazy. Then it hit me, the sound out of the preamp to the receiver should be very good, so I set the EQ to direct mode which bypasses the adjustments of the EQ. I had to up the gain on the preamp after this since the EQ was boosting the level. Voila! That did it. Everyone is right that the X4 presents a wide and immersive soundstage. All the different pieces of percussion, acoustic and electric bass, piano, guitars, and vocals are all smooth and clear. I may keep this as the regular set up bypassing the EQ, and just using the EQ on tape and CD. This is my first tube set up, so I don't think I'll be making and tube changes for now. Definitely a great product, great performance, at a great price. I recommend it.
M**S
Tried this to replace the built in pre-amp on my €150 denon turntable and it made the sound very flat and uninteresting, it's a waste of money.
M**T
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.
A**É
Erg goede kleine buizenvoorversterker voor je platenspeler. Geluid is erg goed. Heb hem nu een dik jaar in gebruik en kan geen min punten benoemen. Daarnaast ziet het er ook mooi uit naast je platenspeler. Minpunt is de koptelefoon uitgang. Deze is dermate slecht dat ze die beter hadden weg kunnen laten. Staat in schril contrast tot de rest.
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