Fosi Audio V3 Mono Power Amplifier 2-Pack
- 240 W at 4 ohms, one amp per speaker
- TPA3255 chip, PFFB feedback
- THD 0.006%, SINAD 101 dB, SNR 123 dB
- XLR/TRS balanced and RCA inputs, gain selection
- Swappable NE5532 op-amps, DIP8 sockets
- Auto power and signal sensing
- 24 months manufacturer warranty
Last refreshed Jun 20, 2026 · Based on the Amazon listing and published specifications, not hands-on testing.
A compact, very clean mono power amp for adding power to one speaker or building out an AV receiver. You need one per speaker, and the power supply is not listed in the box.
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ASIN: B0DQ8FR9GHModel: V3 MonoCategory: Stereo Amplifiers
Overview
Adding a dedicated amp to each speaker, you build a stereo or multi-channel system from these Fosi mono blocks, or let an AV receiver drive them through balanced or RCA inputs. Post-filter feedback reduces the load sensitivity common to Class D designs.
Very low distortion with balanced inputs lets a modest budget drive demanding speakers cleanly. Each unit powers only one speaker, and the box contents list only a quick start guide.
Who it's for
Hi-fi tinkerers who like rolling op-amps and home theater owners with underpowered receivers get clean extra power. People wanting a simple integrated amplifier with volume and inputs for a pair will find two of these awkward.
Pros and cons
- Very low distortion
- Balanced XLR and TRS inputs
- Swappable op-amps for tuning
- Auto power sensing saves energy
- One amp drives only one speaker
- Power supply not listed as included
- Weight and size not listed
Performance notes
Clean output comes from the class D amp chip with post-filter feedback, which holds frequency response steady across different speaker loads. The chip is bonded to the chassis so heat spreads through the case. Balanced inputs reject noise over longer cable runs from a receiver.
Specifications
| Brand | Fosi Audio |
|---|---|
| Model | V3 Mono |
| Capacity & performance | |
| Output Power | 240 W at 4 ohms |
| Cooling | Full-body chassis heat dissipation, side vents |
| Warranty & support | |
| Warranty Description | 24 months manufacturer |
| Other details | |
| Number of Channels | Mono |
| Thd | 0.006% |
| Snr | 123 dB |
| Audio inputs | XLR / quarter-inch TRS balanced, RCA single-ended with gain selection |
| BuiltIn Media | Quick start guide |
| Additional Features | Auto power and signal sensing, four-layer PCB |
| Amplifier chip | TPA3255, Class D, PFFB |
| Op amps | NE5532, replaceable DIP8 |
| Sinad | 101 dB |
Frequently asked questions
Can the Fosi Two V3 Mono connect to my AV receiver?
Yes. It works as a power amplifier for multi-channel AVRs, taking balanced XLR/TRS or RCA inputs.
How many Fosi Two V3 Mono amps do I need for stereo?
Two. Each one drives a single passive speaker.
Can I change the op-amps in the Fosi Two V3 Mono?
Yes. The stock NE5532 op-amps can be swapped for DIP8 dual discrete op-amps such as Sparkos SS3602, MUSES02, OPA2604 or Burson V5i, V6 and V7.
Is a power supply included?
The listed box contents are a quick start guide only. Confirm the power supply with the seller.