Fosi Audio Box X4 Phono Preamp with JAN 5725W Vacuum Tubes for MM Turntable Phonograph Record Player with Volume Bass Treble Control

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.

It's a unique combination of tube phono preamp, component preamp + headphone amp and for the price it's ridiculously good value. My current amp has no headphone jack and with the X4, I now have the option to listen to vinyl with my headphones. It has plenty of power to drive my headphones to extremely loud levels. This preamp has bass and treble controls that allow me to adjust the sound heard through the headphones as well as the speakers - I never seen this feature on a phono preamp and love it. It came with 2 GE 5654W tubes. They are a very nice tubes and actually cost about $15 each, so that’s $30 of the value right there. One of the tubes had a slight bend in the pin that I had to bend straight to get it to fit in the preamp socket (typical problem with tubes…they are delicate). It has red LEDs that light up the tubes that make it look cool. The unit itself is built like a tank (solid metal casing). Attaching my record player to the preamp was simple and the sound quality is amazing! The sound using these tubes is rich and detailed and being able to adjust the bass and treble really lets me dial in the sound for different speakers. If you plug an aux cord into the unit, the phono preamp turns off and defaults to the aux input (gotta pull out aux and then the phono preamp comes back on). Overall I’m amazed at how good of a phono preamp this is for the money. The headphone and aux input preamp are just icing on the cake. Love this X4 phono preamp!!!

The phono preamp sounds surprisingly great with every cartridge I throw at it. Plenty of detail, punch, warmth but not dull at all, with a nice quiet background, too. The tone controls are legitimately useful, with logically-chosen frequencies for a change. The X4 is worth the price for the phono preamp alone, imo. But the headphone output sounds boxy. It's tinny, lacking low end AND high end. It might come in handy if you need a basic monitoring function but that's about it. One other thing I don't like; the cheesy lights that make the tubes glow unnaturally. Totally unnecessary. They could have taken the money they spent trying to make this preamp more appealing to gamers and spent it on better circuitry for the headphone out. Overall I'd give the Box X4 2.5 overall stars because of the headphone output and fake lights. However, the phono preamp itself sounds SO GOOD that I have to up it to 4 stars. This preamp easily outperforms the phono preamps in my Denon receiver, my Denon mixer, and my Pioneer 250MKII mixer. If you buy it for that and not for the headphone amp I think you'll be pleasantly surprised if not shocked!

This was just what was needed in order to bring out the bass from the at-lp120x turntable that I got for Christmas. The turntable has a line out setting but it sounded tinny, could not get any solid bass from playback(all of the other playback devices did not have this issue). The tone adjustments work great and makes the adjustments easy. Only been using a few short days and I hope to get long term use of this wonderful piece of equipment.

This is my first tube anything, so I don't really know what to expect. Before getting into the sound, beware of the build quality. The unit I ordered first showed up with a slightly messed up socket that caused the tube pins to bend. I tried bending them back in place, but ultimately couldn't get them lined up properly and the tube shattered and cut my hand. The replacement showed up showed up fine and I was able to install the tubes easily Out of the box, the unit with the included tubes sounds ok. Not a huge difference from my TT's built in pre. They're oddly bassy and a bit hollow sounding. The real winner is this unit combined with the recommended replacement tubes. The bass tightens up while still retaining a solid punch. Around 12o'clock is the sweet spot for me. Maybe around 1o'clock on the treble knob adds a nice extra sparkle. But again, this is with the replacement tubes. The included tubes don't EQ as well. This is going directly into a set of Edifier active speakers with the EQ set at 0 The headphone jack is a huge disappointment, especially considering that's almost the sole reason I bought this. I tried on a pair of Sennheiser HD 599's and Audio-Technica M40x's. The full sound coming out of my speakers was completely gone and no amount of EQ brought it back. The treble seems to come through, but not the bass. Even with the volume turned down low for listening on headphones, I could hear and feel the bass coming out of my speakers if I dimed the bass knob without hearing any change on the headphones I'd say this is about a 3.5/5 because of how cheap and upgradable the unit itself is, provided you get one that passes quality control and doesn't have a bad socket. The included tubes are forgettable and hard to justify using when a better set is only around 25 bucks. The onboard EQ is nice and can make some tubes shine more than others. Worth getting with replacement tubes for just starting out

I bought this for the GE tubes and tone control.....not my first tube preamp... set it up... no value markings on the tube boxes... are they even matched? oh well...had to turn this more than 3/4 the way up ... very weak....after that too much noise....I have a Fosi X3 on another system sounds strong...with the GE tubes... brought both systems to the same amp ..noticeable output difference... X4 very weak. I then tried swapping the tubes...no appreciable output difference...swapped powersupplies.. again no difference...must be the unit..... Contacted Fosi...".Hello, Victor Really sorry for the inconvenience! Please contact our after-sale and technical support team, they will help you fix the issue. The email address is attached, look for your reply! Sincerely, Kylie" run around.....#1 ok sent the whole issue over to R&D Engineer Summer (lol) responded..."To help us continually improve the product and verify root causes, please record a video to show the behavior of both phono preamps at the same sound system with maximum volume. " Really a video about low output??...hmmm lets see how that has too many variables....... Anyway sent a video of me packing the whole thing up and sending it back....(with very high output).. Its a shame the X3 performs very well was expecting the same quality .....NO QC at all.. no Tube biasing... no understanding of how to troubleshoot and no understanding of customer service.... Oh lord ... why cant we make these in the US, Japan, or a country that cares..... If you buy this...it may be like playing the lottery....if you get a good one.....

I really don't get all the negative reviews about this preamp, I always read them first also YT recommended this one. I am new to vinyl. My last turntable was an all in one unit. I paired this preamp with a Fluance turntable and powered speakers. Setup was very easy and sounds great. And the value was so good maybe later I will try another preamp just to compare sound quality but for right now I'm very happy with the preamp.

I am using this with a Fluance RT85 Reference High Fidelity Vinyl Turntable Record Player with Ortofon 2M Blue Cartridge and a Denon receiver with passive speakers. I love many things about this. The sound is lovely and warm, and I love how there are treble and bass adjustments on the front of the box. It was very easy to set up, although the vacuum tubes required a scary amount of pressure to insert. I was afraid that I was going to break them, but I didn't. The only thing that was not satisfactory is the audio that comes out of the headphone jack is really sub-par. It does not seem to be the same audio that is being fed through to my receiver. One of the things that drew me to this was that my spouse wanted to record directly from the turntable to a computer. The headphone jack output with the audio cable was not good enough for this purpose. Luckily though, I can record to my computer running the turntable audio through my receiver's headphone jack. So, if this listening through your headphones or recording from the preamp directly to a computer is something that is important to you, this would not be the product to purchase. Otherwise, I am thrilled with my purchase.