Fosi Audio V3 Mono Power Amplifier 240W
- 240W @4 ohm rated power, one channel
- TPA3255 Class-D chip with PFFB
- THD 0.006%, SINAD 101dB, SNR 123dB
- XLR/TRS balanced and RCA inputs with gain selection
- Swappable NE5532 op-amps (DIP8)
- 48V/5A power supply included
- 24-month manufacturer warranty
Last refreshed Jun 20, 2026 · Based on the Amazon listing and published specifications, not hands-on testing.
A tiny monoblock amp with clean measured performance and balanced inputs, well suited to adding power to an AV receiver or building a stereo pair. One unit drives one speaker, so stereo needs two.
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ASIN: B0D31M3DXYModel: V3 MonoCategory: Stereo Amplifiers
Overview
Wiring one of these compact monoblocks to each speaker adds clean Class-D power to a stereo or home theater system. This Fosi Audio monoblock uses a Class-D amplifier chip with post-filter feedback, plus balanced and RCA inputs and swappable op-amps.
Low distortion and high signal to noise in a small metal box let it boost passive speakers that an AV receiver struggles to drive. Op-amp rolling lets tinkerers tune the sound. Each unit handles a single speaker, so a stereo pair means buying two.
Who it's for
Home theater owners with pre-outs and audiophiles who like tweaking op-amps will enjoy it. Buyers who want a single stereo amp with tone controls should choose an integrated amplifier.
Pros and cons
- Very low measured distortion
- Balanced and RCA inputs
- Auto power sensing
- Compact metal chassis
- One channel per unit
- No volume control listed
- Speaker cable must connect with power off
Performance notes
Post-filter feedback reduces how much the speaker's load changes the sound, a common weakness of Class-D designs. Heat flows into the chassis, so leave space around it. Balanced inputs reject noise on longer cable runs.
Specifications
| Brand | Fosi Audio |
|---|---|
| Model | V3 Mono |
| Dimensions & fit | |
| Item weight | 750 Grams |
| Item dimensions | 5.71 x 4.24 x 1.57 inches |
| Capacity & performance | |
| Output Power | 240 Watts @4 ohm |
| Power & efficiency | |
| Maximum Supply Voltage | 48 Volts (DC) |
| Construction & materials | |
| Material Type | Metal |
| Included components | |
| Included Components | V3 Mono amplifier, 48V/5A power supply, user manual |
| Warranty & support | |
| Warranty Description | 24-month manufacturer |
| Other details | |
| Number of Channels | 1 |
| Thd | 0.006% |
| Inputs | XLR/1/4 inch TRS balanced, RCA single-ended with gain selection |
| Snr | 123dB |
| Amplifier chip | TPA3255 Class-D, PFFB |
| Op amps | NE5532, DIP8 swappable |
| Sinad | 101dB |
Frequently asked questions
Can the Fosi V3 Mono work with an AV receiver?
Yes. It can serve as a power amplifier for multi-channel AVRs to drive high-power speakers.
How many Fosi V3 Mono units do I need for stereo?
Two. Each amp drives a single passive speaker.
Which op-amps fit the Fosi V3 Mono?
It ships with NE5532 and supports DIP8 dual discrete op-amps such as Sparkos SS3602, MUSES02, OPA2604 and Burson V5i, V6 and V7.
Does the Fosi V3 Mono include a power supply?
Yes. A 48V/5A power supply unit is included.