Different price classes - Fosi Audio ZA3 costs roughly 1.7x what Fosi Audio V3 does. Expect it to lead on paper; the question is whether you will hear the difference through the speakers you own.
| Area | Better | Why |
|---|
| Analogue inputs | A | Fosi Audio ZA3 takes more analogue sources - 2 against 1. |
| Shelf space | depends | Fosi Audio V3 takes up about 40% less shelf area (172cm² against 285cm²), and it is 80mm shallower, which is the measurement that decides whether a rack door shuts. |
| Price | B | Fosi Audio V3 costs less - $90 against $150 at list. |
A Fosi Audio ZA3 B Fosi Audio V3
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?
Fosi Audio ZA3 is ahead, but on only 1 of the measured areas, and it costs about 67% more. That is a lot of money for a narrow margin - Fosi Audio V3 is the sensible buy unless a specific feature above decides it for you. Think about the whole system: the roughly $60 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.