Fosi Audio V3 – Review

Fosi Audio V3

 | Passive Speaker Amplifier | 

Fosi Audio V3, the fresh new 2 channel speaker amp from Fosi Audio.

The Fosi Audio V3 joins the vast catalog of amps, specifically in the pocket amplifier series offering a Class D, amp with 300W x2 max output.

Despite the cheap price, the V3 inherits advanced features such as pre-out to be used as a preamp and replaceable Op-Amp Chips (MUSES02, OPA2134PA, OPA2604AP)

The Fosi Audio V3 is available in several versions, which might help you save some money:

Before buying, read carefully which PSU is included – Amazon tends to have the 32V PSU model available.

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Fosi Audio V3 Review

Tests & Scores


Accessories & Packaging

The unit comes in the same type of packaging see on other Fosi Audio amps we have reviewed.
Inside you will get:

• 1x power supply
• 1x replaceable orange knob




The Fosi Audio V3 has a classic desktop amp aesthetic and form factor.

The rectangular shape with curved angles gives it a stylish and versatile look while the use of an external PSU allows the unit to maintain a very small footprint.

Both the top and bottom of the amp has a perforated area which works as a ventilation system combined with an aluminum heatsink in the casing – smart ventilation seen on $3000+ DAC-Amps that we have reviewed in the past.

On the front panel you will see a clean section where you can basically find a tiny power light and a volume knob – which comes in black from the factory but you can replace it with an metallic orange one that comes bundled with the unit.

The bottom is equipped with 4 rubberized feet that do an optimal job keeping the amplifier in place.

The exact dimensions of the Fosi Audio V3 are: 166x105x35mm and a weight of 547g (1.2lbs)



Operation & Control

The Fosi Audio V3 has a plain simple control system centered on a single knob.

The main knob seen on the front panel controls volume and is also a power on-off controller – the V3 does not have a IR remote nor BT connectivity.

The potentiometer of the V3 uses a taper a pot logarithmic control instead of a linear pot, which allows a more precise and detailed control of the volume ranges that are most commonly used.



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Construction & Build

Made entirely of metal, the Fosi Audio V3 is an outstandingly robust device that feels like a premium product despite the friendly price.

Not a single piece of the amp wobbles nor rattles, the knob is smooth as butter but firm at the same time while all the connectors plug securely but not excessively as of being uncomfortable to plug in and out.




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The V3 connections are found on the rear panel and include:

• RCA input

• 2 channel Stereo Banana plugs
• 1x pre out


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The small size of the Fosi Audio V3 might make it look harmless but, the amp is quite powerful delivering 300W x2 (4ohm).

On top of that, the V3 hides a pack-full of premium audio components beneath the case, which include:

• TI TPA3255 power amp chip
• 2x TI NE5532 op-amps (replaceable)
• Japanese ELNA capacitors
• German WIMA output caps
• Japanese Sumida audio inductors
• Japanese NCC filter capacitors

It is fair to highlight that the amp has a multi power supply compatibility from 24V to 48V, the voltage and amper of the PSU that you match to the amp will determine that max power output reachable by the device.

For example:

• 24V 4.5A PSU: max output 70W
• 32V 5A PSU: max output 125W
• 48V 5A PSU: max output 260W
• 48V 5A PSU: max output 300W

Soundwise, the Fosi Audio V3 presented excellent results during out testings and had no difficulty at all driving 2 full-sized 3-way floorstanding speakers.

The amp does not emit any sound nor adds any audible hiss; in fact, the amp is so clean that while not listening to music you might wonder if it is even turned on as not a single hint of noise is present.

The potentiometer showed an accurate and smooth control of volume levels (though remember that this is not a linear pot); additionally the device was 100% free of scratching potentiometer noises.

Moreover, the were no pops while turning on nor off the device at any given moment.

Overall, the amp showed a full, wide and rich sound that was able to amplify the source signal with impeccable performance.

In addition to this, our measurements revealed that the amp does not adds any alteration of the frequency response of the source, keeping the signal and sound signature with high fidelity and pureness to your source style.

The amp offers an excellent value for money but do not expect fancy functions like EQ, bass control, treble control nor wireless connectivity.

Sound Technical Specifications:
• Max Power Output: 300Wx2 @4Ω
• SINAD: 88dB
• SNR: ≥110dB
• Terminating Impedance: 2-8Ω
• THD: <0.003%
• Power Amp Chip: TI TPA3255
• Op-Amp: TI NE5532 x2
• Power Supply: 32V/5A, 48V/5A
• Input Range: DC 24V-48V
• Frequency Response Range: 20Hz-20kHz(±1.2dB)



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Scores Scores

Fosi Audio V3 Scores

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Frequency Response (raw)

Fosi Audio V3 Frequency Response Curve and measurements


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Fosi Audio V3 Technical Specifications

Max output300W x2
Pre outYes
Speaker ampYes
Subwoofer ampNo
Replaceable Op-Amp ChipsYes
Replaceable KnobsYes

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Fosi Audio V3