The Fosi Audio ZA3 has been floating around audio groups for a while, and it’s easily one of the most talked-about amps from Fosi Audio. After seeing it pop up again and again, I got curious. I wanted to know if the chatter came from real performance or just noise. So, I spent some time living with it in everyday setups, focusing on how it actually sounds rather than just what the specs say.
What surprised me early on was how flexible this small amp really is. You can place it on a PC desk for near-field listening, pair it with a turntable as a straight power amp, run it with a subwoofer, or switch it into mono and use two units for left and right speakers. That freedom makes the Fosi Audio ZA3 appealing if you’re building a hi-fi system slowly or enjoy testing different layouts over time.
One thing I enjoyed during testing is how focused the ZA3 feels. There’s no DAC, no Bluetooth, and no apps involved. It’s just clean power. That keeps the signal path simple and lets you choose your own DAC, phono stage, or streamer without worrying about extra circuits affecting the sound. In a market full of feature-packed mini amps, a straightforward power amp feels refreshing.
The Fosi Audio ZA3 embraces a clean, minimalist design. Up front, it features a solid orange-finished volume knob and two well-built switches for XLR/RCA input and stereo/mono output. Every control feels firm and purposeful, with no unnecessary decoration.
On the rear, you’ll find balanced XLR and RCA inputs, a subwoofer output, sturdy speaker terminals, and the power input. The speaker posts tighten securely, great news for users who frequently swap cables. Ventilation holes along both sides help manage heat during extended sessions.
Overall, the Fosi Audio ZA3’s design is practical, durable, and unmistakably Fosi, complete with clear labeling and the brand’s signature orange accents, making setup straightforward even for newcomers to power amps.
Inside, the amp uses the TI TPA3255 chip, with a signal-to-noise ratio rated at 106 dB and up to 2 x 190 watts at 4 ohms in stereo mode. All of that matters less than how it sounds, but it gives context to what this small box can do.
For more options and comparisons, check out my guide to the best Fosi Audio amplifiers to see how the ZA3 stacks up against other models in the lineup.
A quick note for setup: the RCA inputs are placed fairly close together, so thicker cables with bulky connectors may touch. It’s not a major issue, but slim RCA plugs work best for a tidy fit.
When it comes to source quality, the difference is clear. High-resolution files from Tidal HiFi and FLAC sources reveal far more texture and clarity than Spotify’s compressed streams. For that reason, I’ve stopped using Spotify for testing until its lossless option arrives.
Interestingly, my speakers aren’t particularly high-end, and that turned out to be an advantage. Their slightly muddy midrange makes it easier to detect how much an amp can clean up or open the sound.
One of the most intriguing features of the Fosi Audio ZA3 is its support for op-amp swapping, a feature typically found in higher-end hi-fi amplifiers. This design choice gives listeners the freedom to fine-tune the amplifier’s tonal character based on their preferences or system synergy.
The ZA3 allows you to replace op-amps for the left and right channels, the subwoofer output, and the XLR input stage, opening up a range of possibilities for subtle but meaningful sound adjustments. Whether you’re chasing smoother highs, a richer midrange, or tighter bass control, the right op-amp combination can help shape the amplifier’s overall presentation to suit your taste.
You don’t have to worry about counterfeit parts either; Fosi Audio sells genuine op-amps directly through their store, ensuring quality and compatibility. Official upgrade options include popular choices like the Burson V7, SparkoS Labs SS3602, MUSES02, and OPA2134PA.
It’s important to note that op-amp rolling isn’t necessary to enjoy the Fosi Audio ZA3. The stock configuration already provides clean, balanced performance that will satisfy most listeners. However, for hobbyists who enjoy experimenting, swapping op-amps can be a rewarding way to personalize the amp’s sound and learn more about how small circuit components influence audio character.
While premium op-amps can be pricey, they offer a hands-on way to evolve your system without replacing the entire amplifier. Think of it as fine-tuning your hi-fi experience. You can start with the factory setup, then experiment as your curiosity and budget allow.
Fosi Audio even provides a step-by-step guide video on safely replacing op-amps on the ZA3, making the process approachable even for beginners. With a bit of care and patience, you can transform the ZA3 from a great amplifier into one that’s uniquely yours.
For the Fosi Audio ZA3 sound test, you can check out the full demo on my YouTube channel, where I evaluated the amplifier in a stereo configuration using a single unit. For streaming, I connected the pre-out from the Fosi Audio MC331 to the ZA3 using a FiiO 3.5 mm to dual RCA cable, ensuring a clean signal path and consistent performance during playback.
The ZA3’s volume knob is set around the halfway point, while overall volume control is handled through the Fosi Audio MC331 preamp. When paired with the Fosi Audio MC331, the ZA3 immediately gained an extra layer of warmth and musicality. The MC331’s preamp section smoothed out the highs while adding body to the midrange, creating a presentation that was both rich and engaging.
During testing, I cycled through a diverse mix of genres, from Santana’s expressive, guitar-driven rock to Jacky Cheung’s vocal-focused ballads, to get a sense of how the combo handled different textures and dynamics.
While listening to Taeyeon’s Panorama album “Set Myself On Fire,” the ad-libs and background vocals come through crystal clear, and the overall warm vocal presentation feels open and forward.
The results were impressive: instruments sounded more open and natural, the soundstage expanded, and vocals locked firmly at the center with better separation and spatial clarity at my listening position. Together, the MC331 and ZA3 delivered a balanced, lively performance that combined the ZA3’s precision with the MC331’s warmth, resulting in a sound that was both detailed and emotionally engaging.
For vinyl playback, I connected my Rega Planar 1 turntable to a Rega phono preamp, then routed its RCA outputs directly into the Fosi Audio ZA3. This direct connection minimized the signal chain, letting me hear the amplifier’s raw tonal character without coloration from additional components. The setup revealed the ZA3’s clean midrange detail, natural dynamics, and smooth top-end response, particularly noticeable with well-pressed vinyl records.
I played several Japanese pressings, such as Momoe Yamaguchi’s “Sayonara No Mukougawa” and Kimiko Kasai’s “Vibration.” The results were equally impressive; the midrange gained depth and air, vocals became more articulate, and the presentation felt less boxed in. It’s the kind of improvement that makes older recordings feel freshly alive.
The tight and controlled midbass of the Fosi Audio ZA3 brings a new level of enjoyment to vinyl listening. Unlike amplifiers that exaggerate the lower frequencies or blur midrange details, the ZA3 maintains impressive precision and timing. Bass notes sound firm and well-defined, supporting the music rather than overpowering it.
Want to get better sound quality out of the Rega turntable? Check out these turntable upgrades for Rega.
The Fosi Audio ZA3 does run warm after long sessions, but nothing alarming. Ensuring good airflow or using a small USB fan keeps it comfortably cool. I use the 48V/5A power supply, which provides ample headroom and helps drive more demanding speakers without strain. So far, I’ve had no overheating issues, even during extended listening.
After all the testing, I can confidently say I’m really impressed with how the Fosi Audio ZA3 performs. The bass is tight and controlled, vocals sound clear and natural, and the midrange feels balanced with a nice touch of midbass presence. The soundstage remains open and airy, giving instruments plenty of space to breathe.
Power is no issue either with my power-hungry Jamo 3-way speakers; I rarely need to push the volume past five percent. By the time the knob hits around the 6:40 mark, the amp easily fills my entire living room.
Even when paired with modest speakers, the improvement was noticeable. The ZA3 managed to open up the soundstage and reduce the midrange congestion I had noticed with other amplifiers, bringing more life and clarity to every track.
Looking ahead, adding a second Fosi Audio ZA3 to run in mono mode for dedicated left and right channels remains one of the most exciting upgrades for this setup. It’s great that Fosi gives you that upgrade path without replacing your entire setup. I’m also excited to experiment further with op-amp swapping to fine-tune the ZA3’s sound signature, but for now, I’m just going to enjoy it as is.
Previously, I accidentally blew my full-range speakers during an energetic Tyler, the Creator session! I’ll be replacing them soon with a better-quality pair of full-range speakers, which should help bring out even more of what this amp is capable of. Once everything’s set up, I can’t wait to run another round of ZA3 sound tests to hear how it performs with improved speakers and different op-amp configurations.
If you enjoyed this review, stay tuned for more hi-fi gear tests, vinyl listening sessions, and audio photography content coming soon.
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