Fosi Audio MC331
- 2 reviews
- Fosi Audio
Fosi Audio MC331
- 2 reviews
- Fosi Audio
$129.90
- Authorized Dealer · Tech Support · 30-Day Returns
Why it stands out
Best for
Not ideal for
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Setup guide
How to connect
What you should know
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Frequently asked questions
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Official product information provided by Fosi Audio
The following product descriptions, specifications and images are provided by the manufacturer.
Fosi Audio MC331 is a compact tube integrated amplifier combining digital and analog source selection, speaker amplification, headphone listening and preamplifier output.
Its replaceable tubes, illuminated VU meter, remote control and 105W × 2 maximum output at 4Ω make it a flexible desktop or bookshelf-speaker hub.
Why it stands out
All-in-one audio hub
Combines a DAC, integrated speaker amplifier, preamplifier and headphone amplifier in one compact chassis.
Five source inputs
Accepts Bluetooth, USB, optical, coaxial and RCA sources with remote input switching.
Tube character with visual appeal
Replaceable 5654W-family tubes and a warm VU meter add adjustable tube character and a retro presentation.
Flexible system expansion
Drives passive speakers while pre-out and 3.5mm headphone outputs support additional listening configurations.
Best for
- Desktop and small-room passive speaker systems
- Users switching between computer, TV, Bluetooth and analog sources
- Headphone and speaker listening from one compact component
- Listeners who enjoy replaceable tubes and VU-meter styling
Not ideal for
- Turntables without a built-in or external phono preamp
- Systems requiring HDMI ARC
- Passive subwoofers that need a dedicated powered subwoofer channel
EMiUZEK Buying Notes
- MC331 is an integrated amplifier and can directly drive 4–8Ω passive speakers.
- Its RCA input is line level; a conventional turntable requires a phono preamp.
- Pre-out is for an active subwoofer or downstream amplifier; it is not a passive subwoofer output.
Frequently asked questions
Can MC331 drive passive speakers directly?
Yes. Connect 4–8Ω passive speakers to its speaker terminals.
Does it include a phono input?
No. A turntable needs a built-in phono stage or a separate phono preamp before the RCA input.
Can I connect a TV?
Yes, through optical, coaxial or RCA audio output. MC331 does not provide HDMI ARC.
Can I use headphones?
Yes. It includes a front 3.5mm headphone output.
Can I add a subwoofer?
Yes. Use pre-out with a powered subwoofer or another compatible downstream device.
Are the tubes replaceable?
Yes. Officially listed compatible families include 6AK5, 6AK5W, 6Zh1P and 6J1.
HOW TO CONNECT
Passive speaker system
Source: Phone, computer, TV or line-level source
Connection: Bluetooth, USB, optical, coaxial or RCA
Output: Speaker terminals
Target: 4–8Ω passive speakers
Note: Select the matching input and begin at low volume.
Headphone setup
Source: Digital or analog source
Connection: Bluetooth, USB, optical, coaxial or RCA
Output: 3.5mm headphone output
Target: Wired headphones
Note: Disconnect or lower speaker output before private listening.
2.1 system with powered subwoofer
Source: Digital or analog source
Connection: Chosen source input
Output: Speaker terminals + pre-out
Target: Passive speakers + powered subwoofer
Note: Use the subwoofer's own level and crossover controls for integration.
Technical Specifications
Core specifications
| Feature | Specification |
|---|---|
| Product type | Tube integrated DAC / amplifier / headphone amplifier |
| Maximum speaker output | 105W × 2 at 4Ω |
| Speaker impedance | 4–8Ω |
| THD | ≤0.03% |
| SNR | ≥100dB |
| Power supply | 24V / 4.5A |
Inputs and outputs
| Feature | Specification |
|---|---|
| Inputs | Bluetooth, USB, optical, coaxial, RCA |
| Outputs | Passive speaker terminals, pre-out, 3.5mm headphone output |
| Bluetooth codecs | SBC, AAC |
| Replaceable tubes | 6AK5, 6AK5W, 6Zh1P, 6J1 |
Recommended System Setup
| Setup | Connection |
|---|---|
| Desktop speakers | PC → USB → MC331 → Passive speakers |
| TV audio | TV optical output → MC331 → Passive speakers |
| 2.1 system | Source → MC331 → Passive speakers + powered subwoofer |
Additional Product Content
Fosi Audio product comparison
Compare the two compact Fosi Audio integrated amplifiers by the differences that most affect system matching.
| Feature | MC331 | MC351 |
|---|---|---|
| Product position | Tube DAC / integrated stereo amplifier | High-power 2.1 digital integrated amplifier |
| Built-in speaker amplifier | Yes | Yes |
| Maximum output | 105W × 2 at 4Ω | 165W × 2 + 350W at 4Ω |
| Main inputs | Bluetooth, USB, optical, coaxial, RCA | Bluetooth 5.3, USB, optical, coaxial, RCA |
| Speaker output | Stereo passive speakers | Stereo passive speakers |
| Passive subwoofer output | No | Yes, dedicated amplified output |
| Line-level pre-out | Yes | Yes |
| Headphone output | Yes, 3.5mm | No |
| Tube stage | Yes, replaceable tubes | No |
| Best use | Compact tube stereo and headphone system | Powerful passive-speaker 2.1 system |
What's in the box, manuals and downloads
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