I really loved the **Fosi Audio MC331**. I had always wanted a tube amplifier on my desk, and even though the tubes are small, they give it a very fun look and plenty of personality.

What surprised me most was the sound. For such a compact unit, it sounds very good, with a pleasant presentation and enough power to drive my **Monitor Audio RX6** without feeling out of place at all.

In my setup, the MC331 actually ended up feeling a little small physically on the desk, but performance-wise it delivers much more than its size would suggest. It is a very enjoyable little amplifier, easy to use, good sounding, and visually different from the usual desktop gear.

For anyone who has always wanted to try a tube-style amplifier without going into a large or complicated setup, the MC331 is a very fun option.

Glowing (unlike the tubes)
I love my amp, I even figured out the usbc connection (one day the optical) the only mild disappointment is the glow of the tubes… they simply don’t look bright

very impressive piece. quite a looker, tubes are awesome, tone controls are handy, easily pushes decent desktop speakers, easy to setup 2.1 and runs any iems to full advantage, love it, remote makes it versatile, footprint is minimal, not my first Fosi amp, totally not my last (mono power blocks next, watch out for coupons )

The charged arrived broken. The ligth turn on but Don’t genérate voltage. The amplifier sound it’s amazing

I will bought it again

A lot of music for the money. It´s conected to my computer and a pair pf monitor speakers Magnat S10B with 86 db and it plays with energy and control. For that price I´m stunned.

Compact unit with multiple inputs, I use optical for CD player, coaxial for streamer, USB for desktop, Bluetooth for iPhone, still have a RCA for extra...

This little unit surprised me. Have it matched with a pair of Sony CS5M2 Speakers. It ticked all the boxes, Bluetooth, Optical & RCA. Sounds great, the tubes give a nice warm sound with a little punch!

it looks like an superior developed Tube Enigma for the audiphyle which survived in the cold war

it sounds like a thunder

great

I changed my audio system from 40 years old pre-main AMP (marantz PM-94) to this MC331.
New technology is quite good even for elderly people like me.
The sound is quite natural and clear.
The usage is simple and easy with enough interface for any audio equipment and sound source.
I love this MC331 so much.

Aunque el tamaño es menor a lo que pensé, ésto se compensa con su calidad de sonido y versatilidad para la reproducción desde diferentes fuentes. Deben mejorar el embalaje, instalando desde la planta los bulbos. Gracias!

He comprado este equipo hace algunos meses, tuve un inconveniente al principio pero el equipo de fosi impecable atención post venta, destacable.
En cuanto al equipo cambie de válvulas por unas NOS GE 5654w y suena muy bien, mejora notablemente respecto de las stock .
Ecuación costo/beneficio es imbatible

Amazing sound for this size.give my b&w CM1 a New life !

Really great product

I bought my MC331 to replace my P4. And if you're reading this, then you understand without me needing to say it that I'm not really using it in its wheel-house use case as an all-in-one. Right now it's literally just my preamp (running 3.5mm stereo to unbalanced XLR to power a pair of ZA3s in bridged mono). This should mean that the upgrade was minimal -- especially in the first nanosecond -- but boy-howdy would that implication have turned out to be mistaken.

Straight out of the box the MC331 is at once both warmer (duh), more resolving (um, half-duh?), and yet also somehow with more rhythmic drive. PRAT and warmth are, in my experience, very difficult to find in the same component, but this little baby does both, immediately and effortlessly. An easy, easy, EASY recommendation, and with the added benefit that we've so far only been talking around, instead of about:

The MC331 is a piece that can be experimented with, modularly, on an almost infinite basis. With two pairs of stand-mounts to flip between, you're looking at a minimum of 10 combinations for its application to your system: DAC only (x2), Preamp only (x2), DAC and Preamp but not Amp (x2), Preamp and Amp but not DAC (x2), and Amp only (x2).

The obvious benefit is that the first-day experimentation is much more likely to yield a winning formula: The chances of needing to send this piece back because it didn't work in one's system are zero. But there's a much bigger, sneakier, and much less frequently talked about advantage to having modularity in one's system:

It reduces the impulse to buy more new gear.

I have two pairs of stand-mounts and switching between them always has the effect of quelling my online shopping itch at a literal stroke. With the MC331, a person can do this over and over again -- thus promising an extremely long period during which new sound is just one power-down-and-reconnect away, for $0.

Suggestions for Fosi: 1st, many Fosi products are weight-distributed in a way that ignores how the connections at the rear apron will shift the center of gravity rearward. This gives Fosi gear a pronounced "pitch-up moment" (as pilots would have it). Since Fosi doesn't install MCAS on my stereo equipment without telling me, I can't kill 100 passengers due to a faulty angle of attack sensor -- but I *can* get out of bed full of positive energy for the day, only to emerge into the living room to find one or more of my pieces upside-down on my very hard floor, behind the rack, because one of my cats just wanted a place to sit.

I'm not a designer or engineer, but I strongly suspect that other manufacturers build into their designs an awareness of this issue and subtly overweight the front of their pieces, with the post-connection center of gravity far nearer to the ideal position.

Second, this piece is clearly designed for either a desktop application or for person just starting out, and both of those groups will be looking at smaller speakers and/or headphones. With only a 3.5mm preamp output jack on the rear, in addition to standard speaker terminals, connecting either headphones or a subwoofer will be impractical in most applications, near-impossible if one wants both.

Since the entry point on this piece is so low (I paid $104 for mine including shipping after cashing some Fosi points), I would strongly recommend adding some manufacturing cost to address these quibbles, then tacking the resulting cost-increase onto the price without concern for diminishing the product's reach.

If everything else about the MC331 were literally exactly the same, but it had an easy way to connect headphones and a subwoofer, and it wasn't going to throw Rose and Jack off the fantail into the propeller every time my cat got on it, I'd consider it a red-hot steal at $209.99. Something to think about, anyway: Most beginners and desktop solution-seekers aren't expecting to have ALL of their electronics needs addressed for $210.

Otherwise, bravo Fosi. As per usual.

It's kind of a shame, really: We've all gotten so accustomed to this company hitting things out of the park, every single time, that a cartwheel-inducing smash success like this struggles to break through our baked-in perceptions of value. I'm reminded of a recent election cycle in the US, in which a journalist said, "All [Candidate A] needs to do to win this debate is solve a 16-sided Rubik's Cube while performing an appendectomy on stage; all [Candidate B] needs to do to win is not set the building on fire and spray the audience with gasoline." At this point, alas, Fosi Audio is solving a 16-sided Rubik's Cube with a $104 piece of kit that doesn't strike most hobbyists as worth this much time to read about.

But then, maybe that's better. We, after all, will always know what we've got here, and we'll always keep appreciating the consistency of this peerless company's commitment to delivering audio-listening excellence on an absolute scale for literal ...

Very happy with my Amp. It looks awesome, and the sound quality is very well passed to my speakers!

I am very satisfied with sound and design. MC 331 with original tubes are easy to install and they work perfectly. Amp has enough power to push my passive Wharfedale Laser 50 speakers to work like a charm.

Very warm sound. It changed the way my headphones listening is appreciated

Nice warm sounding amp. This is a great amp for headphone and nice soft/relaxing music. It also has no problem powering my bookshelf speakers

Brilliant amp! Works great.

Incredible sound from this little box. Punching!

I purchased this item based on information acquired from a source familiar with quality sound. I have a great pair of Martin Logan speakers and realized from sources I did not have the correct combination of amp to sound. First off I needed a DAC unit, a quality Bluetooth interface and the Martin Logan's love a tube amp. The Fosi MC331 fit all the necessary items. The quality sound I receive from the MC331 to the Martin Logan's is incredible and the price point makes the MC331 unbelievable !

Fosi Audio MC331 Tube Integrated Bluetooth Amp