The MC331 is an integrated amplifier with built-in DAC by Fosi Audio that delivers 105 watts x 2 channels maximum into 4 ohms. Fosi publishes no 8 ohm rating. It was released in 2024. It is a 2-channel design using a Class D output stage. The MC331 is a hybrid, with vacuum tubes in the preamplifier stage feeding a solid-state output, running 2x 5654W. Speakers connect via binding posts. A minimum impedance of 4 ohms makes it compatible with a wide range of loudspeakers. It has a built-in DAC, so you can play digital sources directly with no separate DAC unit needed. The Fosi Audio MC331 has an MSRP of $130.
There are 2 Fosi Audio amplifiers in our database. Below you can see the main specs of these amps.
Fosi Audio Integrated Amplifier Series
Performance Specs
One of the most important factors when deciding on an integrated amplifier is its power ratings and compatibility with your speaker's impedance requirements. The Fosi Audio MC331 is rated at 105 watts RMS into 4-ohms. Fosi Audio provides this wattage at a THD (Total Harmonic Distortion) of 0.03% which is an important indicator of distortion at the given values (lower THD is better).
Here are the main highlights of its performance specs:
- 105 watts into 4-ohms
- 4-ohms Min Impedance (allows compatibility with a wide range of loudspeakers)
Wiring more than one pair of speakers to it? Check the load first →
When pairing the Fosi Audio MC331 with a passive Bookshelf (Stand mount) or Passive Floor Standing (Tower) speaker, you have to check if their Max Power Range is below the max wattage of the amp for the given impedance levels.
Operating your amp outside of this max range may damage the speakers.
Inputs and Outputs
Besides the performance specs of the Fosi Audio MC331, the next important feature set that you have to evaluate is the input and output selections that it offers.
Fosi Audio MC331 has total of 1 Analog inputs .
Inputs
- Total Number of Analog Inputs: 1
- Yes Optical Digital Input
- Yes Coaxial Digital Input
- USB Input
Outputs
- Speaker Outputs
- Stereo RCA pre out Preamp Outputs
- Yes Headphone Output
Bluetooth Connectivity
Fosi Audio MC331 features built-in Bluetooth for wireless music streaming from your Bluetooth-enabled devices such as Apple iPod/iPhone/iPad, Android smartphone/tablet, Windows PC, Mac computers/laptops.
Among the amps in the same price range, these are the 5 amps that have Bluetooth Connectivity:
Phono Input
Fosi Audio MC331 doesn't have a phono input so in order to play your vinyl albums, Fosi Audio MC331 has to be paired with a Phono Preamp that is MM (Moving Magnet) or/and MC (Moving COil) depending on your cartridge type.
Subwoofer Output
Fosi Audio MC331 has Stereo RCA preamp outputs which can be used to connect to a powered subwoofer via an RCA cable ( as long as your sub supports this connection).
Check our
Powered Subwoofers page to find a subwoofer that will work with Fosi Audio MC331 amp and your speakers.
DAC and Digital Music
The Fosi Audio MC331's built-in DAC allows the connection of digital sources directly, eliminating the need for an external DAC.
Fosi Audio MC331 Pros and Cons
Drawn from the published figures on this page, not from listening.
- ✓Hybrid design, with a valve stage ahead of a solid-state output section.
- ✓Class D output stage, so it runs cool and wastes little power as heat - which is how it fits in a small case.
- ✓Built-in DAC, so a TV, computer or streamer can connect digitally with nothing in between.
- ✓Bluetooth for playing straight from a phone.
- ✓Pre-outs (Stereo RCA pre out) leave room to add a power amplifier or an active subwoofer later.
- ✓Headphone output.
- ✓Has tone controls.
- ✓Has VU meters.
- ✓At 254mm wide it fits where a full-size component will not.
- ✗Only 1 analogue input, so a second source means unplugging the first.
Fosi Audio MC331 External Dimensions and Weight
Fosi Audio MC331 has external dimensions of (H x W x D) 2-11/16 x 10 x 2 inch (68.6 x 254 x 50.8 mm ).
Base Surface Area
Base surface area of an integrated amplifier may become an important decision factor when the space in your room or desk is limited.
The base area of the Fosi Audio MC331 is approximately 129.0cm2 / 20.0inch2.
- Width: 254.0mm (10")
- Height: 68.6mm (2-11/16")
- Depth: 50.8mm (2")
- Weight: —
- Base Surface Area: ~129.0cm2 / 20.0inch2
- Volume: ~0.9 liter / 0.2 gallon
Available colors
Fosi Audio MC331 is available in Black color options.
| General |
| Brand |
Fosi Audio |
| Full Model Name |
Fosi Audio MC331 |
| Release Date |
2024 |
| Amplifier Type |
Integrated Amplifier |
| Number of Channels |
2 |
| Amp Class |
Class D |
| Amplifier Technology |
Hybrid (vacuum tube and solid state) |
| Tubes |
| Input and Driver Tubes | 2x 5654W |
| Total Tube Count | 2 |
| Performance |
| Watts RMS per Channel into 8-ohms |
N/A |
| Watts RMS per Channel into 6-ohms |
N/A |
| Watts RMS per Channel into 4-ohms |
105 watts |
| Frequency Bandwidth |
|
| THD |
0.03% |
| Minimum Impedance |
4 |
| Signal to Noise Ratio |
N/A |
| Digital Music |
| Built-in DAC |
Yes |
| Bluetooth |
Yes |
| WiFi |
No |
| CONNECTIONS |
| Total Analog Inputs |
1 |
| Phono Input |
No |
| Optical Digital Inputs |
Yes |
| Coaxial Digital Inputs |
Yes |
| USB Input |
Yes |
| Preamp Outputs |
Stereo RCA pre out |
| Headphone Output |
Yes |
| Removable Power Cord |
|
| Speaker Connectors |
Binding posts |
| PHYSICAL SPECS |
| Height |
68.6mm (2-11/16") |
| Width |
254.0mm (10") |
| Depth |
50.8mm (2") |
| Weight |
— |
| Available Colors |
Black |
| OTHER |
| Tone Controls |
Yes, bass and treble |
| Parts Warranty |
|
| Labor Warranty |
|
How much power does the Fosi Audio MC331 have?
The Fosi Audio MC331 delivers 105 watts x 2 channels maximum into 4 ohms. Fosi publishes no 8 ohm rating.
Does the Fosi Audio MC331 use vacuum tubes?
Partly. The Fosi Audio MC331 is a hybrid - vacuum tubes in the input and driver stages feed a solid-state output stage, so it takes some of the character of a valve amplifier with the power and the load tolerance of a transistor one. It runs 2x 5654W.
How long do the tubes in the Fosi Audio MC331 last?
Output valves are a consumable. In normal domestic use a set lasts somewhere between about 2,000 and 5,000 hours - a few years for most people - and they degrade gradually rather than failing outright. Input and driver valves last far longer, often the life of the amplifier. Check the warranty card before you buy: valves are almost never covered by the amplifier's own parts warranty, and are usually warranted separately for 90 days to a year.
What amplifier class is the Fosi Audio MC331?
The Fosi Audio MC331 uses a Class D amplifier design. Class D is a modern switching design that runs cool and wastes very little energy as heat, which is how makers fit high power into a compact, light chassis.
Does the Fosi Audio MC331 have a built-in DAC?
Yes. The Fosi Audio MC331 has a built-in DAC, so you can feed it a digital source directly without buying a separate converter.
Can I connect a turntable to the Fosi Audio MC331?
No. The Fosi Audio MC331 has no phono input, so a turntable needs an external phono preamp (or a deck with one built in) before it can be connected.
Does the Fosi Audio MC331 have Bluetooth?
Yes. The Fosi Audio MC331 supports Bluetooth, so you can stream straight from a phone, tablet or laptop.
Does the Fosi Audio MC331 have a headphone output?
Yes. The Fosi Audio MC331 has a Yes-inch headphone output on the front panel for private listening.
How much does the Fosi Audio MC331 cost?
The Fosi Audio MC331 has a manufacturer's list price (MSRP) of $130.
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