Different price classes - Audioengine N22 G2 costs roughly 2.4x what Fosi Audio V3 Mono does. Expect it to lead on paper; the question is whether you will hear the difference through the speakers you own.
| Area | Better | Why |
|---|
| Speaker load rating | A | Fosi Audio V3 Mono is rated down to 2 ohms against 4, so it is the safer partner for a low-impedance speaker. |
| Built-in DAC | B | Audioengine N22 G2 has a DAC on board; the other needs an external one, which is another box, another power lead and another purchase. |
| Analogue inputs | evenly matched | The same number of line-level inputs (2). |
| Headphones | depends | Only Audioengine N22 G2 has a headphone output. Worth something if you listen late, nothing if you never do. |
| Amplifier class | depends | Fosi Audio V3 Mono is Class D and Audioengine N22 G2 is Class A/B. Class D runs cool and draws almost nothing at idle; Class A/B runs warm and is the long-established mainstream choice. Modern examples of both measure well - judge by the rest of the page. |
| Price | A | Fosi Audio V3 Mono costs less - $110 against $269 at list. |
A Fosi Audio V3 Mono B Audioengine N22 G2
depends neither is better in the abstract - it turns on your room, your system or how you will use them. Only specs published for both amplifiers are judged; anything missing on either side is left out rather than guessed.
Which should you choose?
Neither runs away with it - they trade advantages. Let the "depends" rows and the speakers you already own settle it. If you already own a DAC or a streamer, the built-in one is money you are paying twice for, and Fosi Audio V3 Mono becomes the more rational buy. Think about the whole system: the roughly $159 saved by taking the cheaper one would buy better speakers or a subwoofer, which does more for the sound than the difference between two competent amplifiers.
What a spec sheet cannot show: how either sounds with your speakers, how the controls feel day to day, and what the app is like to live with - which is where most all-in-one amplifiers are actually won or lost. Power figures are the manufacturers' own and are not measured to a common standard, so treat small differences as noise. If you can hear both, that will tell you more than any row above.