Fosi Audio V3 Mono Power Amplifier for Home Audio Speakers, Mini Monoblock Class D Amp with TPA3255, 240W for HiFi Home Theater AVR Receiver Component, RCA/XLR Balanced Inputs

I bought 4 of these Fosi v3 monoblocks with 2 x 48volt/10amp power supply units. They are being used to drive Tannoy XT8F revolution tower speakers in a vertical mono/bi-amp mode ( i.e. each speaker is connected to 2 monoblocks with a shared PSU ). After an initial 24 hour burn in, they opened up to produce a wonderfully transparent, dynamic and powerful sound. The treble is clean without edge or grain, the midrange is very clear with excellent low level detail resolution and the bass is well controlled, defined, extended and surprisingly hard hitting. The overall tonal balance is quite neutral with just a hint of treble forwardness. The Fosi v3 small form factor, belies its capability when producing a very large soundstage with terrific focus on, and the space between, the musical elements within it. Plus the stereo imagery is precise with good centre focus, coherence and decent depth. I was originally sceptical about the V3 mnbks when I heard, read and saw ( on You tube ) the rave reviews about them. Now I have confirmed for myself, their exceptional performance for the money. Compared to my 2 other, much more expensive power amps, from Marantz and Emotiva, they more than hold their own. Highly recommended. Additional information:- Everything said about the v3 monoblocks remains the same, ( if anything they're even better sounding than when they were first reviewed, due to slightly less treble forwardness ). However they do become hot during use. Therefore I recommend using a low noise fan ( if you can't put them on/in a well ventilated shelf/cabinet ). DON'T stack them on top of each other without adding feet to separate them.

A pair of these with a wiim pro plus streamer, with variable output, will out perform so called "proper hi-fi", costing 10 to 20 times the price. Believe me these are an absolute steal. I use the with monitor audio silver 6 floorstanders, £1000 a pair and they sound magnificent.

These little boxes have really surprised me. I was using a Rega Elicit R that has powered most of my speakers for the past 10+ yrs and it has served as an excellent amp. I recently purchased a set of Kef R3 Meta's and something in the sound I was hearing suggested they just weren't getting enough power from the Rega. I was considering NAD, Hegel or Nord as my next move, when I stumbled across these (Fosi v3 mono). For the price I thought I could test what 240W (4 Ohm) would do to the Kef's before committing to my next amp, whilst also experimenting with monoblocks. I've been using them for about 10 hrs now and I can honestly say they are amazing, not just for the money amazing, they are simply very good at what they do. Noticeable clarity and separation improvements, engaging and tight bass and I can play music at a sensible volume without feeling like I'm losing anything in the mix. I'm not saying I won't still get a big power amp down the road but these will certainly stay in use for the foreseeable.

These amps sound fantastic, loads of presence and power at lower volume, exactly what I wanted. However, presumably to keep costs down, they require external power supplies and suffer from a serious design flaw - overheating. Putting aside the PSU issue which I could live with, the cases are just not adequate for dissipating heat, I've never come across class D amps which run so hot. This is surely going to limit the life of the units and means that they need to be very well ventilated, this is just not practical. A real shame as they are sonically the absolute shiznit for the money. If a redesign cures the heat issues, I'll certainly reconsider.

Beautiful little boxes with a BIG sound. I have upgraded the opamps to VirtualHifi Supersonic V1, 4 of them at €25 each, and the sound is amazing. Paired with a set of Wharfdale 12.3 I don’t need a sub (if you like normal music with normal bass levels). My go-to tracks for testing are Bruno Mars, Versace On the Floor, and Alfie Boe, Bring Him Home. Unbelievable bass control on the Bruno Mars track, deep and controlled, not boomy. For Alfie Boe, it sounds like you are there watching the performance live. Like all hifi reviews it is purely subjective and you should listen yourself to find out if it is right for you. The best thing about buying on Amazon is you can send it back if you don’t like it.

Wasn't sure if these were going to be a 4 or 5 star review. As other commentators have said, they do run hot; burning hot, over 60C. They sit at 40C in standby. I worry about the heat affecting electrolytic capacitor lifespan. I bought four for my bi-amping project, (I was replacing my 4 channel 3886 hybrid 'scraplifier') and the quiescent current draw must have been enormous. So, on advice, I replaced the 48v psu (x4) with a 32v psu (x4). It added an extra hundred quid to the project, but I was eight hundred in to it by now, so it seemed rude not to. And, WOW, I'm still producing 100w (x4) into 8 ohms. And with a usb dac, everything reaches FSD (full volume) at the same point. And now they run 'cool' at about 40C in-use and just above room temp in standby. Sound? Acoustically invisible. Confidence? Much better. Value for money?...Well, it works for me. You'll have to decide for yourself. Four and a half stars.

Very poor quality control. As soon as I hook a pair of these v3 mono blocks up that they was out of phase,, fosi website had previously put out a statement addressing this issue and assured potential customers this has been corrected since 2nd August 2024 and to buy from them or reputable sellers such as fosi or Amazon. But this is not so.. upon checking the internal wiring as suggested by fosi it's clear to see that one of my amps was indeed wire incorrectly. I also noticed the one amp PCB was dated late 2023 and the other Amp late 2024, the Amp dated 2023 arrived in a box that didn't look new and had what looked like cup rings on the box and the Amp itself was covered in dirty hand prints and binding post had scuff marks indicating previous use, this same Amp start to smell of burning components and in about an hour of been on started to let the magic smoke out, not so magic as these fumes are fairly toxic. I'm had high hopes for these little Amps as they have great reviews in the main, maybe I was one of the unlucky ones, but I wounder how many buyers don't realise the lack of bass and depth is due to the amps being wired out of phase. Pictures to follow. Amazon didn't give a satisfactory conclusion

My setup is modest budget-ftiendly kit, I already had an SMSL a300 amp wth the volume turned all the way up and the volume controlled by a cheap passive preamplifier. After lots of research & believing all the hype, decided to 'upgrade' to these Fosi V3 Monos. Admittedly there was loads of detail in the music with them (but no more than with the a300) but whereas the sound with the a300 was full bodied & rich with a big, deep immersive soundstage, the Fosis sounded weak, thin & compressed. I could swap the op amps to try and get a similar sound to the a300 but the pair of these standard units were already £50-ish more than the a300 and 4 decent op amps could be £300-ish (yes you could really do with swapping 4). Save your money and get just one a300 instead, if you really want to try dual mono buy two and put them in bridged mode to turn them into monoblocks, it will still be cheaper than the V3 Monos + decent op amps.. If you really want to try op amp rolling a Fosi ZA3 might be the better option, if you buy a single ZA3 and want to swap the op amps you only need to buy 2, if you decide to buy a second ZA3 you can turn them into monoblocks and if you do that you'll only need to swap ONE op amp on each unit so you can take one of the upgraded op amps out of the first ZA3 and put it in the second one, you'll still only need the pair you've already bought - you'll need 4 for the V3 Monos...

Van en la línea de las opiniones que ya se han escrito. - Pequeños, bien acabados, con un ladrillo de transformador y un filtro más pequeño que puedes esconder. - Llama la atención lo que se calientan aunque si consideras que la carcasa es de aluminio y que el transistor que amplifica va pegado a ella, es normal. Si que es buena idea tenerlos separados. Yo les he puesto unos disipadores de ordenador, pero es que quiero que vayan uno encima del otro. - Cómodo el disparador que los enciende cuando se enciende el DAC. Parecen sonar un poco mejor por la salida XLR que por la RCA, pero es marginal. - Suenan bien para el precio que tienen y lo que se puede esperar de ellos. Valen para mover altavoces de gama baja, para los de gama media también pero no les sacarás todo el jugo. - Con los amplificadores operacionales que lleva (dos cada uno), el sonido es aceptable: buenos bajos, quizás les falta textura, medios un pelín chillones y agudos un poco exagerados. No he puesto otros, pero estoy seguro de que se notará la diferencia. Eso sí, si no tienes cuidado la suma de lo que gastes se te irá a 500 €. - Suenan fuerte. Creo que puedes mover cualquier cosa, aunque me parece que cuando subes el volumen el sonido se resiente. Si lo notas y te gusta darle caña, busca una fuente más grande; para el resto, a volúmenes normales, no hace falta. - No engañan. Muy buena opción para escritorio si no buscas la perfección. Quizás cambie los opamps en el futuro. Creo que eso les puede subir de nivel. - Cuidado con los tornillos que aprietan los cables de los altavoces que son de plástico y se rompen enseguida si aprietas un pelín. Si usas conectores tipo banana, no hay problema. Rev 05/2025. Suenan mejor pasadas estas semanas. Supongo que es cosa del rodaje. Todo suena más orgánico y redondo. Son unos matagigantes y un chollo por el precio. Ahora no le veo mucho sentido cambiar los OPA salvo que tengas el oido muy fino y compres sobre seguro. No creo que lo haga. Sigue siendo muy buena opción para altavoces hasta 1000 € aunque lucen bien con unos más caros. Eso si, no les sacaran todo el jugo. Subo una estrellita.

The four channels of the TPA3255 amp chip are all utilized in a parallel arrangement in this amp. This means the dampening factor on your speakers is x2. If you have a 6ohm speaker this amp sees it as a 12ohm load. Add to this great topology the feedback filter placed at the output stage (PFFB) and you’ve got two unique features above and beyond most class D amps in this price range or higher. It makes for a great sounding powerful amp that can drive just about anything. These can get hot so I immediately replaced the pitiful squirt of thermal compound with Thermal Grizzly Duronaut (which basically performs extremely high without drying out). I then removed the rubber feet from the bottom and strapped on a 150mm aluminum heatsink with a thermal pad between. I then use the amps upside down so the heat goes straight out the top heatsink. Normally it spreads through the bottom and around the enclosure creating a cute little oven for your components. Roll op amps to improve sound, use at least a 48V 5A power supply and Bob’s your uncle !

Incroyables ampli pour un tarif hallucinant. Équipé en 7.2.2 dans une salle dédiée hifi et home cinéma, j'ai acheté 3 amplis pour alimenter mes 3 avants Dali Rubicon. Je redécouvre la musique et les films. Plus d'impacts, plus de précision, plus de clarté, plus d'immersion. Plus, plus, plus. Ça a un impact sur l'ensemble du système. J'avais acheté l'an passé un ampli de puissance à 1400€ et 3 canaux déçu de l'amélioration. Avec ces amplis c'est le jour et la nuit Ils chauffent un peu mais sans plus dans un meuble ouvert. Je n'en reviens toujours pas du gain qualitatif. Je conseille à tous mes amis d'investir au moins pour la stéréo. Un seul inconvénient trop de fils à rajouter ( 6 rca, 3 cordons d'alimentation). Ce n' est pas négligeable mais pas rédhibitoire. Merci Fosi.

This thing rocks. Hear the finest audiophile quality.

Bought new life back to my system sounds great and compact too.