In this video I’m comparing the Fosi V3 Mono vs the Fosi ZA3 Mono, because after my last ZA3 stereo vs mono video a lot of you asked: “Why not just get the V3 Mono?” The big takeaway is that the ZA3 is simply more flexible and cheaper to get going. With the ZA3, the initial setup cost is lower, you get a volume control, you don’t need to buy two units to run a stereo system, and you also get a subwoofer output—things the V3 Mono doesn’t give you out of the box. On the other hand, the V3 Mono has some real advantages if you’re chasing objective performance. It has PFFB, which makes it less load dependent and helps keep the frequency response more linear across different speaker loads. I also talk about heat and practical setup: my V3 Monos run warmer, I used footers for extra airflow, and I wouldn’t stack them. Then I run a sound demo using my ZD3 DAC into the ZP3 preamp (balanced), feeding either dual ZA3 in mono or dual V3 Monos, both stock, each on a 48V/5A power supply, driving my DALI speakers. In my room, I hear the V3 Monos as slightly better in separation/soundstage/clarity, while the ZA3 comes across a bit warmer.