Manufacturer | Fosi Audio |
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Part number | ZA3 |
Item Weight | 1.75 kg |
Product Dimensions | 15.49 x 18.39 x 5.08 cm; 1.75 kg |
Item model number | ZA3 |
Colour | Black |
Voltage | 48 Volts |
Wattage | 235 watts |
Item Package Quantity | 1 |
Plug profile | Surface Mount |
Specification met | FCC |
Batteries included? | No |
Batteries Required? | No |
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Fosi Audio ZA3 Balanced Stereo/Mono Amplifier HiFi with TPA3255 Chips, Mini Audio Amp Monoblock with XLR RCA Inputs and 12V Trigger-in for Desktop Bookshelf Passive Speakers with 48V5A Power Supply
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Purchase options and add-ons
Item dimensions L x W x H | 15.5 x 18.4 x 5.1 centimetres |
Voltage | 48 Volts |
Manufacturer | Fosi Audio |
Maximum supply voltage | 48 Volts |
Minimum supply voltage | 230 Volts |
About this item
- Dual-Mode Innovation: This new generation mini amplifier offers both stereo and mono modes, adapts flexibly to your diverse needs, allowing seamless mode switching. In stereo mode, it delivers a robust output of up to 180W, while in mono mode, the power soars to a maximum of 235W. Pair two ZA3 units in mono configuration to create a powerful audio system, significantly enhancing your listening experience.
- Richer Connectivity: Debut amplifier with balanced input and trigger in, the ZA3 features a balanced combo audio signal input connector supporting both XLR and 1/4" TRS plugs. This design minimizes interference and reduces noise floor. The 12V trigger-in connector enables synchronization with other devices, streamlining the process of turning on/off without individual operations.
- Audiophile-Grade Components: The ZA3 features the TPA3255 high-end Class-D amp chip and utilizes premium Japanese NCC, ELNA, and German WIMA capacitors, and Japanese Sumida inductors for exceptional audio quality. With a SINAD rating of up to 89dB, an SNR of up to 106dB, and a low noise floor of only 150μV, it delivers exceptional clarity and low distortion.
- Advanced Heat Dissipation: Based on V3's groundbreaking heat dissipation design, we upgraded ZA3's cooling system by featuring a larger chassis, moving vents to the sides, and adding dust covers to achieve better ventilation for a sustained and stable high power output.
- Enhanced Scalable Fun: Personalize your audio experience with the op-amp rolling feature! The ZA3 stocks five swappable op-amps for left and right channel outputs, balanced input, and subwoofer output. Experiment with compatible DIP8 dual op-amps such as Sparkos SS3602, MUSES02, OPA2604, OPA2134PA, OP249, AD827, RM4558, LM4562, LME49720HA, etc. to fine-tune your sound to perfection.
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Additional Information
ASIN | B0CLP4T5L7 |
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Customer Reviews |
4.6 out of 5 stars |
Best Sellers Rank |
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Date First Available | 24 Oct. 2023 |
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Fosi Audio ZA3 Balanced Stereo/Mono Amplifier HiFi with TPA3255 Chips, Mini Audio Amp Monoblock with XLR RCA Inputs and 12V Trigger-in for Desktop Bookshelf Passive Speakers with 48V5A Power Supply
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Discover Fosi Audio - Your HiFi Solution! We're a tech-driven brand, crafting innovative audio products around the world. Our vision: Affordable excellence for each consumer. Our mission: Redefining HiFi with cost-effective innovations. Join Fosi Audio on this unique audio journey!
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Get to know about Fosi Audio
For the past 5 years, we have been designing and developing audio products for real life, aiming to provide a perfect blend of premium acoustic performance with a modern, elegant design.
Why do we love what we do?
We’re not limited by what’s possible now. With a bold vision for the future of audio products, we painstakingly develop advanced technology and innovative research to make it a reality.
Why choose Fosi Audio?
We use meticulous production technology, combined with low-key modern industrial design, to present the sound as clear and pure as flawless crystal.
Product Description

High-Performance & High-Fidelity.
Fosi Audio ZA3
The next generation balanced dual-mode Class-D power amplifier. Fosi Audio's first amplifier supporting both stereo and mono modes.

Amplifying Your Voice, Shaping Our Innovation
At Fosi Audio, behind every innovation, there's a story. The birth of the ZA3 amplifier is just such a story, centered around our users. After the launch of the V3 amplifier, we gathered innumerable feedback from passionate audiophiles. They expressed a desire for us to develop an even better amplifier based on V3.
- Input: RCA, XLR, ¼”TRS; Output: Stereo, Mono
- SNR≥106dB; THD<0.006%; SINAD: 89dB
- Frequency Response: 20Hz-20kHz (±0.1dB)
- Rated Power Output: Stereo 180W*2 @4Ω; Mono 235W @4Ω
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Flawless XLR Balanced Input Support
Delivers pure sound, initiating a high-definition auditory adventure with unmatched clarity.
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PBTL Mono Mode Support
More power output to elevate your stereo HiFi system to new heights.
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TI TPA3255 Amp Chip Integrated
Enabling superior sound and ultra-low distortion across the audio band with Class-D efficiency.
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Advanced Heat Dissipation Design
Enhanced cooling with larger chassis, whole-body heatsink, and side ventilation with dust covers.
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Swappable Op-Amps
Compatible with DIP8 dual op-amps. Roll them to get your preferred sound signature.
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Logarithmic Potentiometer
Helps to achieve a fine volume tuning to match human ear's auditory characteristics.
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Separated Digital & Analog Modules
Optimized circuit board layout protects core audio modules from interference for a purer sound.
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12V Trigger Sync Interface
Smooth synchronization with other devices for easy one-click power management, unifying your audio system's operation.

Aluminum Alloy and One-Piece Molded Chassis
Delicate sandblasting and smooth beveled edges, exuding a premium, exquisite texture and high-end appeal.
Comparison Chart
2.0 CH Amp | Type | 2.0 CH Amp |
180W x 2 / 235W x 1 | Rated Power Output | 230W x 2 |
RCA+XLR+¼”TRS | Input | RCA |
Passive SPK +Sub-out | Output | Passive SPK +Pre-out |
Treble& Bass Control | ||
<0.006% | THD | <0.003% |
≥106dB | SNR | ≥110dB |
2.0 CH Amp | Type | Monoblock Amp |
180W x 2 / 235W x 1 | Rated Power Output | 240W x 1 |
RCA+XLR+¼”TRS | Input | RCA+XLR (¼”TRS) |
Passive SPK +Sub-out | Output | Passive Speaker |
Treble& Bass Control | ||
<0.006% | THD | <0.006% |
≥106dB | SNR | ≥123dB |
2.0 CH Amp | Type | Bluetooth 2.0 CH Amp |
180W x 2 / 235W x 1 | Rated Power Output | 220W x 2 |
RCA+XLR+¼”TRS | Input | Bluetooth + RCA |
Passive SPK +Sub-out | Output | Passive Spk+Pre-out |
Treble& Bass Control | | |
<0.006% | THD | ≤ 0.03% |
≥106dB | SNR | ≥ 108dB |
2.0 CH Amp | Type | 2.0 CH Amp |
180W x 2 / 235W x 1 | Rated Power Output | 230W x 2 |
RCA+XLR+¼”TRS | Input | RCA |
Passive SPK +Sub-out | Output | Passive Speakers |
Treble& Bass Control | | |
<0.006% | THD | ≤ 0.3% |
≥106dB | SNR | ≥ 90dB |
Customer reviews
Customer Reviews, including Product Star Ratings, help customers to learn more about the product and decide whether it is the right product for them.
To calculate the overall star rating and percentage breakdown by star, we don’t use a simple average. Instead, our system considers things like how recent a review is and if the reviewer bought the item on Amazon. It also analyses reviews to verify trustworthiness.
Learn more how customers reviews work on AmazonCustomers say
Customers praise this amplifier's sound quality, with one noting its decently quiet noise floor, and appreciate its build quality, power, and value for money. They particularly value its clarity and depth, with one customer highlighting its stunning clarity and resolution, while another mentions how it increases depth and detail greatly.
AI Generated from the text of customer reviews
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Customers praise the amplifier's power.
"What a great little amp. I have had a few expensive HiFI set ups in my life, but now that I have downsized, I wanted something smaller...." Read more
"...The ZA3 is a power efficent and small device with just about everything you'd want for a high end audio system...." Read more
"...The momo mode strikes me as a gimic as you get very kuttke extra power, so I am running each amp in 2 channel mode bi amping each speaker which..." Read more
"Hi. Absolutely fantastic amp. I have it connected to 20 year old mission m762i speakers. Sounds fantastic. Great bass and treble and mid too!..." Read more
Customers appreciate the build quality of the amplifier.
"...Recommended for those looking for a less expensive, but still good quality, amplifier base." Read more
"...I'll also add that the build quality is great, and it looks extremely nice in person." Read more
"...Build quality seems excellent otherwise." Read more
"Good quality and good service." Read more
Customers find the amplifier to be an amazing value, with one describing it as an inexpensive audiophile amplifier.
"First up it's good value for money and has very nice clear highs,top end of treble, and is handy for desktop and near listening, great for students..." Read more
"...As such, this is a good value unit for the feature set." Read more
"Great sound ,great build amazing price. Get 2 and run in Monoblock you will not be disappointed." Read more
"Cheap but impressive...." Read more
Customers praise the amplifier's clarity, with multiple reviews highlighting its greater resolution and depth, and one customer noting its accurate low frequency representation.
"...The LM 4562 Op Amps...provide stunning clarity and resolution. Even without this modification..the ZA3 is a truly innovative product...." Read more
"First up it's good value for money and has very nice clear highs,top end of treble, and is handy for desktop and near listening, great for students..." Read more
"...the sound(feel) is tight and controlled, provides very accurate low frequency representation. The build quality is fantastic, hasn't missed a beat...." Read more
"Arrived, been playing for a few hours. Excellent sound, so clear, powerful betters amp that cost £1k," Read more
Customers appreciate the amplifier's depth, with one mentioning it increases detail greatly, while others describe it as rich and incisive.
"...is that this isn't just about volume/gain...it increases depth and detail greatly. Is it necessary? No...." Read more
"...It has a rich, natural sound that reminded me very much of old Class A analogue, but cleaner...." Read more
"...But the sound is clean, incisive and well-balanced (at least to my ears)...." Read more
Reviews with images

Inexpensive audiophile enthusiasts amp with lots of upgrade options
Top reviews from United Kingdom
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- Reviewed in the United Kingdom on 14 March 2025What a great little amp. I have had a few expensive HiFI set ups in my life, but now that I have downsized, I wanted something smaller. This, when hooked up the the WiiM Ultra that I also bought recently and a good pair of bookshelf speakers (Dali), sounds way more impressive than it should. The fact that I can use this as a mono or stereo is something I've never come across before, and that opens up its versatility even more. Recommended for those looking for a less expensive, but still good quality, amplifier base.
- Reviewed in the United Kingdom on 26 November 2024So...in my opinion...this is were Class D now defeats Class A-B amplifiers.
I have these with the ZD3 - running in mono. The installed NE5532 op amps in the ZA3's are ok but after doing research I found the best op amps that are inexpensive. The LM 4562 Op Amps...provide stunning clarity and resolution. Even without this modification..the ZA3 is a truly innovative product.
The ZA3 has dual amplification chips...not a single unit. This provides the greater resolution and fidelity.
The ZD3 already has these installed and the resolution is superb.
Don't forget the ZA3 has balanced XLR inputs..which is class leading in terms of inputs. In such a small unit !
The sound is so refined and detailed.
Buy yourself a power supply filter for your wall sockets and some ferrite cores and this further improves detail for any sound system.
I did buy a second ZA3 - added the LM 4562's of which 3 are required for left - right & XLR input. 5 - if you have a subwoofer.
The 12v trigger is so convenient...just by a good length 3.5 jack splitter cable to control both ZA3's with the remote.
So I purchased the extra ZA3 and upgraded to mono. Each dual amp chip in each ZA3 - now controls one speaker - providing greater power and detail. I'd say it has boosted speaker detail and power delivery by 40%.
What's interesting is that this isn't just about volume/gain...it increases depth and detail greatly. Is it necessary? No.
Other amps in Class D - have only one amplifier chip and can't match the resolution of the ZA3. What's interesting...if you check vastly more expensive amps - check what op amps they are using. Very often it is the standard NE 5532's or OPA.
The LM 4562 chips are sort of a hidden gem in op amps...fast and detailed and the fosi ZA3 is hardware compatible with their greater resolution and depth. It's only £10 for two chips...but make sure they are genuine.
I have wharfdale 9.1 diamond speakers...and for the first time..I modded the crossover to film foil capacitors which I didn't think I would be capable of doing. Just takes a little time and I have never soldered before...but I gave it a go and it improved the quality of output greatly.
The ZA3 is a power efficent and small device with just about everything you'd want for a high end audio system.
I think it is a genius product that is vastly underrated. Even prestigious audiophiles are using the ZA3 in mono configuration.
- Reviewed in the United Kingdom on 2 March 2025Hi. Absolutely fantastic amp. I have it connected to 20 year old mission m762i speakers. Sounds fantastic. Great bass and treble and mid too! Even on tricky to plat bass heavy tracks. Beyond my expectations
Cheers
Quick update - i bought another one and use then to power left and right speakers in stereo mode. The difference is amazing both in terms of Clarity and power.
- Reviewed in the United Kingdom on 7 March 2024Second edit: Fosi Audio saw my message below and has contacted me to offer a free replacement without me having to ship the other one back. Really good customer service.
Warning: Everything I wrote below is true, but now I'm having scratchy noises while adjusting volume, just like an elderly amp with an analogue pot. Not sure how to get it fixed without shipping to China. Extremely disappointed.
I got one of the first batch of these, so I've had it now since December. From the moment I hooked it up to my desktop system (usb out from computer, Dragonfly Red as a dac, Q Acoustics 3020s, REL TZero subwoofer) I was blown away. It has a rich, natural sound that reminded me very much of old Class A analogue, but cleaner. Notes have body and weight and presence, and it throws up a big soundstage with very precise placement of instruments and vocalists. I can easily say it sounds better than amps I might have spent over £1,000 on 10 years ago.
There are a couple of annoying things about it, however. I'm not fond of using a volume knob as a power switch, and I hate having the stereo/mono switch in a place it could accidentally be knocked, though that's never happened in my case. (It seems a lot of people are really enamoured with the idea of using two of these as monoblocks, but I don't have that kind of power requirements.) Honestly, it's hard to imagine being able to use more power than it already has with the 48v brick unless you live in a detached house and have a very large listening room or very hard-to-drive speakers.
This is a fantastic little bit of kit, and I've had a few through the door as I was working out which I liked best (Marantz PM6007, Aiyima D03 and A07, SMSL AO200 MKII, Topping PA5 II). None of them could quite match it. The Topping comes very, very close and would easily be my second choice because it's so beautifully clean and doesn't put a foot wrong. I just think I like a slightly meatier amp with a touch of warmth, and that's the ZA3. If you're after a less warm sound or if your speakers are really lacking in high end, I might go with the Topping, which also deserves a lot of praise.
I listen to it every day, and I'm still shaking my head at how something so cheap could sound so good. I'm not sure if this is a sign I've been exposed to too much audiophile snake oil over the years or if the quality and implementation of Class D amps has just come astonishgly far in that time.
I'll also add that the build quality is great, and it looks extremely nice in person.
- Reviewed in the United Kingdom on 1 January 2025This is a great little amp. It comes with a large power brick, but this can be tucked out of sight. I m running 2 in mono format and get a great sound stage. The momo mode strikes me as a gimic as you get very kuttke extra power, so I am running each amp in 2 channel mode bi amping each speaker which works well and uses the available power much better. In this mode they compare well with much more expensive big brand hifi amps. I designed and manufactured pwm power amps and speakers in the 90's for Aston Martin, Rolls Royce and other car manufacturers so I'm well versed in this field.
Top reviews from other countries
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João ReisReviewed in Spain on 6 May 2025
5.0 out of 5 stars Muito bom
Amplificador muito bom, boa potência, som claro e limpo e quase não aquece. Recomendado
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Antonio M.Reviewed in Mexico on 11 May 2025
5.0 out of 5 stars Muy buen valor precio
Calidad, y valor precio sin igual. Usando como DAC el Chord 2 suena muy bien.
- H. A.Reviewed in Saudi Arabia on 15 April 2024
5.0 out of 5 stars Fun little amplifier with great versatility for expansion into hifi
I used this amplifier to drive the JBL 530 which is a 6 ohm nominal load and 86 db/w sensitivity speakers and it drives them at all levels easily with no noise whatsoever, the character of this speaker/amp pairing is a bit laid back in mid range, fast and tight thumping bass, slightly rolled off in the treble,
I’ve found the best dynamics with the potentiometer somewhere between 11:00-01:00 o’clock and the windows volume betwen 60-70%(Vrms of 1.95V DAC line-level output), this gives me about 70 db average listening level with 30+ db of dynamics headroom.
I’m looking to try other op-amps in this amplifier and see how it affects it tonally, overall I’m plenty happy for such a good price and lower size profile that this amplifier provides, well done Fosi!
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Muzo35Reviewed in Turkey on 26 August 2024
5.0 out of 5 stars Efsane!! Fosi Za3 Stereo!!
48v 5A adaptörü takıp kendi dahili dac.ı rca ile denedim evet ilgi çekiciydi fakat standart bi d -classtı. Daha sonra 3 adet muses02 opamp sipariş verdim ve elime ulaşıncaya kadar amfinin yanmasını bekledim. Nihayet geldi opampları değiştirdim ve sub opampı devre dışı bıraktım(kullanmadığım için) vee Xlr (cardas golden cross) ları bağlayınca vaaay müthiş ses!!
Birçok pahalı amfiyi sınıfta bırakır çok net!! Opamp yükseltmesi yapıp güzel bir Xlr ile kullanınız şaşırcaksınız....
- Yamen ZeinReviewed in the United Arab Emirates on 4 May 2025
5.0 out of 5 stars Great HiFi democratized!
These small class D amps are exceptional value for money! I have amps that cost 20 times more than the ZA3 but does not deliver even 5 times the performance. I tried this (just for fun) with my power hungry Sonus Faber Sonnetto I bookshelves and it managed to make them sing beautifully up to the max volumes I listen to (70-80 db). I use two of them in mono mode to power my desktop speakers mainly for nearfield listening. The only thing I miss is a high low pass filter for the sub output. This is honestly exceptionally priced HiFi! The performance makes the price a steal! And I am so inclined to build an entire system of Fosi products just to compare its performance to price against my other ridiculously priced higher mid-range systems, which I 'm sure this will give a run for the money! I heard some premium and expensive high-end amps, and this definitely does not compete with them (I mean, come on if you're expecting this!), but for mid-range and other entry level products, I believe this thing is a certified LGK!