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Fosi Audio

Fosi Audio ZA3 Balanced Stereo Amplifier Home Audio Component Mini 2 Channel Mono Amp TPA3255 for Subwoofer Desktop Home Theater Bookshelf Tower Floorstanding Passive Speakers with 48V Power Supply

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Availability: In Stock.
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Arrives Tuesday, Jul 28
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Features

  • 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 150V, 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

Description

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. SNR≥106dB; THD<0.006%; SINAD: 89dB Delivers pure sound, initiating a high-definition auditory adventure with unmatched clarity. More power output to elevate your stereo HiFi system to new heights. Enabling superior sound and ultra-low distortion across the audio band with Class-D efficiency. Easy one-click power management with smooth sync across devices, unifying your audio system. Compatible with DIP8 dual op-amps. Roll them to get your preferred sound signature. Enhanced cooling with larger chassis, whole-body heatsink, and side ventilation with dust covers. Optimized circuit board layout protects core audio modules from interference for a purer sound. Helps to achieve a fine volume tuning to match human ear's auditory characteristics. 1. Addressing Functional Issues 1.1 Left Channel and Mono Setup Problems: Mode Selection: Ensure you've selected the correct mode using the switch on the right side of the ZA3. For stereo sound, the switch should be in the downward position; for mono, it should be upward. Cable Connections: Double-check all input and output cables for secure connections. Faulty or improperly connected cables can cause sound issues. Power Supply: Make sure you're using the appropriate power supply for your device. 1.2 Power On/Off Issues: Power Switch Operation: To turn your ZA3 on or off, press and hold the volume knob for 2 seconds. This feature might be different from other devices you've used, so it's important to familiarize yourself with this operation. 2. Enhancing Audio Sound Quality 2.1 Insufficient Power and Sound Output: Volume Adjustment: If the sound is too low, try turning the volume knob clockwise to increase the volume to an appropriate level. Power Supply and Mode: Understand that the power output varies with different power supplies, speaker impedances, and operating modes. Adjust accordingly to achieve the best sound quality. 2.2 Not Meeting Expectations: Audio Source Quality: For better sound, use high-quality audio files and avoid compressed formats like MP3, which can sound worse when amplified. Speaker Placement: Position your speakers at least 30cm away from walls or corners to avoid muddy bass sounds. Subjective Perception: Remember that audio quality can be subjective. Experiment with different audio sources and settings to find what sounds best to you. 3. Overcoming Compatibility Limitations 3.1 Incompatibility with Speakers or System: Check Impedance: Ensure your speakers' impedance is within the 2 to 8 ohm range supported by the ZA3 for optimal performance. 3.2 Lack of Additional Inputs and No Signal Output: Input Options: The ZA3 supports RCA and XLR inputs. It does not have a DAC function, so it won't provide a signal output. Make sure your audio source is compatible with these inputs. 3.3 Power Adapter Size: Adapter Purpose: The 48V/5A power adapter is designed to meet the higher power requirements of the amplifier, ensuring it delivers its full potential. Its larger size is necessary for this purpose. Note: The product doesn't support Bluetooth. ZA3 TB10D V3 V1.0G ZD3 P4 Q6 Visit the Store Visit the Store Visit the Store Visit the Store Fosi Audio S3 HiFi Music Streamer DAC Preamp TPA3255 Class D Home Audio Mini Speaker 2 Channel Amp 300 Watts x2 Guided by our mission of "Redefining HiFi with Unmatched Value", Fosi Audio continues to fuel its passion for the Hifi industry, ramp up R&D efforts, and co-create new HiFi equipment with users. We pledge to bring more amazing Hifi gear with high value for the price, innovative design, cutting-edge technology, and premium quality, to audiophiles worldwide.

Item dimensions L x W x H: 6.1 x 7.24 x 2 inches


Voltage: 48 volts


Manufacturer: Fosi Audio


Maximum Supply Voltage: 48 volts_of_direct_current


Minimum Supply Voltage: 24 volts_of_direct_current


Voltage: 48 volts


Maximum Supply Voltage: 48 volts_of_direct_current


Minimum Supply Voltage: 24 volts_of_direct_current


Mounting Type: Surface Mount


Number of Channels: 2


Output Power: 235 watts


Package Type Name: Cardboard Box


Maximum Output Power: 235W


Item Dimensions: 6.1 x 7.24 x 2 inches


Specification Met: FCC


Manufacturer: Fosi Audio


Model: ZA3


Brand Name: Fosi Audio


Warranty Description: 24-month manufacturer


Unit Count: 1 Count


Included Components: Fosi Audio ZA3 Power Amplifier x1；48V5A Power Adapter x1；User Manual x1


Part Number: ZA3


Frequently asked questions

If you place your order now, the estimated arrival date for this product is: Tuesday, Jul 28

Yes, absolutely! You may return this product for a full refund within 30 days of receiving it.

To initiate a return, please visit our Returns Center.

View our full returns policy here.

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Similar Products

Top Amazon Reviews

    • Very satisfied but watch out for setup traps
I was replacing an older NAD integrated amp that I really liked. Decided to go class D amp for a replacement. WAY smaller. MUCH less expensive, and this unit has all the functionalities I was looking for at an incredible price (I bought mine for about $130 each on Amazon. Will be using two in mono mode. At first I thought they were defective. PAY ATTENTION TO THE MANUAL THAT WARNS YOU TO CONNECT ALL CABLING BEFORE YOU INSERT THE POWER CONNECTION. If you power the device first, then attach cables, it won't work at all until you detach the power cable and reinsert it. This is no fluke. It happened several times. Attach ALL cabling first, then insert the power connection. Secondly, if you're running it in mono mode the inputs for both units are inserted into the RIGHT side on the rear of the unit. The left channel is disabled in mono mode. This is all spelled out in the manual but it's counter-intuitive at first. As for sound, I'm pleased. I'm sending Tidal or Spotify digital signals to a Fosi ZD3 via bluetooth (works perfectly). The ZD3 is the DAC and connects to the paired Za3s. My speakers are very modest, a HSU powered sub that I've connected to the ZD3 (not the ZA3). Main speakers are HSU HB1 mk2. The ease of use with my iPhone is just fantastic. Essentially any song I want is at my fingertips. Sound quality is very good to my untrained ears. I'm very happy with this purchase. These amps have more than enough power to drive these smaller speakers even at higher volumes than I'd ever naturally want. The fit and finish of the amps is very good. No noise in the volume knob at all but I leave them in a fixed position adjusting volume either at the ZD3 "preamp" or even more commonly with my iPhone volume controls. I've been buying / building stereo equipment for about 55 years. I'm a huge music fan, but I can't hear all the mumbo-jumbo the experts can. I just know these are great little amps for an incredible price, and even one would work nicely in stereo mode. Very happy. Will see how they stand up to time and use. ... show more
Reviewed in the United States on July 12, 2025 by NBO
    • Plenty of power, sounds nice, good support (firmware updates)
Review Image by DH
Review Image by DH
Review Image by DH
Great little amp. My stack is a Wiim amp pro (for streaming and eq), Fosi ZD3 preamp, and Fosi ZA3 with the 48v power supply running in stereo mode. Mostly run from an apple tv sending hdmi to the tv then optical from there. The whole setup was easily under $500. I chose this setup in case I needed more power, I can simply add another amp and run mono, but it's definitely not needed. Runs a pair of Q Accoustic 5020s easily to unlistenable levels in a small/med size room (450sq/ft). I have the whole stack switched with a smart plug and haven't had any issues with powering off or on (unlike my last set of powered Swans speakers which blew up on power up). I was occasionally getting a little pop on power up and also a computerized "bzzzrt" very occasionally during listening. I just googled and found there was a firmware update for the Preamp (no issue with the amp). Just contact Fosi support and they give you the url for the updated firmware. Easy to install with a windows laptop and usb cord. Haven't had either issue since. Really nice to see firmware updates so quickly! So used to products this cheap being treated as "disposable" and not getting real support. I'm very happy with the performance and the support. I think it really helps that there seems to be a lot of love in the stereo community for this and other Fosi products. I hope it continues to get firmware updates in the future. The set looks really clean and very minimal. Used to do the whole rack or shelf system of components, but I'm over it. Most recently, I was using a set of powered speakers because I like not seeing the electronics. But when those failed you basically throw the whole thing away. I eventually had them fixed, but I don't like the idea of a failure being a total loss. So now I like having small separate pieces. I absolutely love the size. Even though the Fosi set looks very nice, I now have my entire multimedia set up hidden behind a small chest and subwoofer as shown in the last picture (please ignore my weird music choice). There is one downer on this product. It has a sub out which is great. But when you connect a subwoofer, it still sends full signal to the speaker outs. At high volumes you can hear the small bookshelf speakers trying to put out bass that's not really needed with a sub. Edit: I forgot my SVS subwoofer has a high pass eq! So now I have the preamp go into the subwoofer and pass through to the amp. The sub out should really be on the preamp not the amp. Weird choice. ... show more
Reviewed in the United States on March 7, 2025 by DH
    • highly recommend this little amp
nice little amplifier; amazing price; super compact; blue tooth connectivity is great
Reviewed in the United States on July 20, 2026 by Brad J. Faltermeier
    • Endgame (for now)
Review Image by Truth Seeker
I dove headfirst into the hi-fi realm at the beginning of the year and not knowing what to expect. I come from a studio set up with active monitors (Adam A7) hooked up to an Audient ID44 audio interface. For my small but amazing bachelor pad, I was actually using an Echo Dot hooked up to a small pair of Presonus Eris 3.5 speakers (Don’t Laugh). Obviously knowing what good sound sounds like, I wasn’t satisfied with that set up. I started looking up amplifiers, Dacs, and bookshelf speakers. Of course people swear by AB amplifiers as better sounding, but I wanted a minimal set up that sounded good without using up too much space. Not that I don’t mind spending more cash, but I also know that you reach a point of diminishing returns. Do I really want to spend an extra thousand dollars for a 5% increase in sound quality? Not me, at least not now. So I began my research. At the beginning of the year I purchased the Aiyima A07 Pro with of course the infamous Sony SSCS5 that everybody seems to have; thank the Cheap Audioman for that. I wasn’t using a DAC, I was streaming straight from my iPhone paired up with Bluetooth. I thought OK this is cool, I can live with this. But then I started binging on more YouTube videos and soon realized that I wanted more. Sound was cool but not great. I would say that the turning point came when I found out about the WiiM Pro streamer. You wanna talk about a life-changing product, that’s it! It literally changed the game for me. From streaming from my TV, tablet, phone, everything... Chromecast, Airplay, Spotify connect, Tidal. You name it! They put all of the pieces together for me and made everything seamless. After a bit more research, I came across the SMSL SU-1 DAC everybody was raving about. As for speakers, I purchased a pair of Polk XT15 to go along with my Sony's. I liked the Sony's, but they were lacking a bit in bass and chose the Polk XT15 because they were on sale on Amazon for $135 and were also significantly smaller than my Sony's while still having a 5“ driver and a better frequency response in my opinion. The highs were crystal clear yet non-fatiguing, and the bass punchier and hefty while the Sony's sounded more boomy in comparison. Beautiful speakers all around and definitely recommend them. Of course you know I didn't stop there though! I started late night binging on YouTube and foaming at the mouth thirsting for more and better gear. Upon yet more research, I realized that everybody was swearing about the new Fosi ZA3, so on launch day, I jumped all over it and purchased it. I swapped out my Aiyima A07, turned on the Fosi ZA3 and my first impression was warmth, wideness, punch. Now don’t get me wrong, the Aiyima A07 Pro is no slouch, and it has served me well throughout the year. I’m still keeping it and putting it in the master bedroom. I love the tone controls, the Bluetooth connectivity, but the Fosi definitely had the “IT” factor. Music was immersive, I started bopping my head, tapping my feet on the ground and busting the nickel in the living room (for those that know about break dancing). I felt it was definitely an upgrade. I also like that it has balanced XLR connections which sound better than RCA and louder. Here's my setup: • Polk XT 15 Bookshelf Speakers • Fosi ZA3 Amplifier • WiiM Pro (Not the Plus) • SMSL SU-1 DAC • Audioblast Speaker Cables • Mogami 2964 RCA Cables • Gotham GAC-1 Pro SPIDF Cable Could you get a better set up? Of course! But then again, do you really need it? The diminishing returns factor kicks in really quick. I mean, It’s easy to become addicted to buying gear. FOMO is REAL! I found that out this past year. New gear is always coming out at a feverish pace, on a monthly basis it seems. but seriously, just go with what you need and sit back roll a fat one, break out the wine, crack open a cold brew and just enjoy the music! With my current rig, I dropped $600 and I’m at the point where I’m happy with my set up. It’s more than good. It’s great. Could I drop an extra thousand dollars on a better DAC and amplifier? YES. Would people notice the difference? Absolutely not! With my current set up, I get compliments all the time. The music sounds amazing, and the ladies love it. Good luck on your journey and remember, diminishing returns! ... show more
Reviewed in the United States on December 30, 2023 by Truth Seeker
    • Like it
I really wanted to like this amp but it just didnt work out with the outdoor sub i am running. It powered an outdoor speaker great. I do wish it had inputs and outputs for speakon connections but the different options it does have work fine. For the short bit i used it, it seemed to run fine. The build quality seemed durable and well made. One small thing I wished it did have was some sort of led’s to show load, clipping and thermal overheating. ... show more
Reviewed in the United States on May 16, 2026 by Jason
    • Highly Recommended even though I eventually returned it. Let me explain.
First, let me say how impressed I am with the ZA3. It packs a huge punch for its size. I own a pair of PSB Stratus Gold i speakers, which are known to be difficult to drive. I bought a Yamaha A-S701 and the Fosi ZA3 just to compare the best I could get for the price in a Class AB and a Class D amp. I ultimately returned the Fosi just due to the amount of extra cables I needed in my particular setup vs the Yamaha 701. I would 100% recommend the Fosi though as it gave me 85% of the performance of the 701 for a small fraction of the price. The Yamaha and Fosi sound about the same TBH. The Fosi also barely gets warm at higher volumes where the Yamaha definitely gets toastier. The Fosi is clear at all volumes with no distortion that I noticed. About my only complaint with the Fosi is that you have to hold down the volume knob to turn it off and on. I would much rather they move the stereo/mono switch underneath and make that the power switch. Do not hesitate to get the Fosi if you are looking for a reasonably priced amp that performs very well. I think a perfect setup would be to have another brand preamp that has 12v trigger connected to this so it would turn on and off with the preamp, but also have a lot more options for inputs. I do have a lot of sources so that factored into my decision. This is a great amp you won't be disappointed with. ... show more
Reviewed in the United States on March 23, 2026 by Sean H Miller
    • Awesome product!
These things are awesome. I love high quality audio and have expensive gear. I recently had a Amp go out on me, and through discussion with several people wh I consider Audiophiles - with the money to support the habit 😂, they kept pointing me to these. My plan was to buy 2of these, run them as mono blocks until my main Amp was repaired (6+ months - if you are into vintage gear you would understand the wait). Anyway -I purchased these and haven't looked back. Supreme sound quality for the money. I am running 2 as mononlockas and they pump out clean power. They don't sound sterile and have really brought the sound stage to life. I am using a WiiM Pro as my streamer then going through a Yamaha head unit for DAC. I cannot explain how something so reasonably priced outperforms gear that costs Thousands more!!! I wish this stuff would have been around when I was younger, I would have saved so much money. 1 last note - you can change te OPAmps on these to change the sound characteristics. A friend did this and they sound even better. Not the opamps he purchased cost almost as much as the amps themselves. Great cost to performance product! Fosi will always be on my list when buying gear in the future. ... show more
Reviewed in the United States on January 30, 2026 by Snafoo
    • Excellent Sounding Versatile Class D Amplifier
Review Image by R. Hing
Review Image by R. Hing
Review Image by R. Hing
Review Image by R. Hing
Review Image by R. Hing
I ordered a Fosi ZA3 from Amazon this past Wednesday and it arrived yesterday morning. Upon unboxing the nicely packed amp and 48V-5A power supply, both pieces were ice cold, so I had to allow for everything to warm up to room temperature before powering anything on. I connected the ZA3 amp to my Audio Research LS7 tube line stage, and played back tracks through my Raspberry Pi 4 running Volumio 3 connected to an SMSL SU-9 V. 2 DAC. Over a period of 2-3 hours, I could hear the sound signature changing from a bright, etched sound with narrow image and small soundstage to a warmer, full-bodied sound whose soundstage expanded beyond the outer boundaries of my modified Klipsch Forte 2 speakers. The image projected slightly in front of the speakers to behind them and grew in height. I could feel the bass lines coming through the floor and felt the impact of some deep notes through the air. With the Klipsch speaker efficiency rated at 98dB, I found myself dialing the volume down a couple steps as the amp burned in. A friend recommended leaving the ZA3 powered on, so I left it on all night with the volume turned all the way down. When I spun some vinyl the next day, I was really impressed with the scale of the soundstage compared to what I heard the previous day. The music has a really solid foundation in terms of imaging and separation. The musicians all have their place in the soundstage, and the tonality is very rich. This amp digs more deeply in the lower bass compared to my Pass DIY Sony VFET Class A amp and the McIntosh MC-240. It’s very dynamic with nice, sustained notes. It’s crazy how great this amp sounds for the $130 I spent on it. In the last photo, the Fosi ZA3 is sitting on top of a Pass DIY Sony VFET push-pull single-ended Class A amp I built several years ago. Next to that is a McIntosh MC-240 tube amp I had rebuilt with new power supply and coupling caps. Over the next several days while I have time off from work, I will compare these amps using my analog set-up, and the above-mentioned digital source: - Technics SL-1200GR - Audio Technica AT33/PTG II LOMC cartridge - Audio Research PH5 tube phono stage - single-ended connection I split my time between two homes for my work. At my other home--an apartment--I plan to take this amp and try it out in the system there: - Bill Neumann (Fix My Dual) rebuilt Dual 1229 idler wheel-drive turntable - Shure V15 Type III MM cartridge - Schiit Mani 2 phono stage preamp - single-ended connection - Raspberry Pi4 running Volumio 3 USB-based streaming source - Denafrips Pontus 2 R2R DAC - balanced connection - Schiit Freya+ Tube/SS line stage with OS GE 6SN7's with side-getters (gain stage) and Tung Sol 6SN7's (driver stage) - balanced connection - Pass DIY Aleph J Single-Ended Class A power amp - balanced connection - KEF LS50 speakers It's with this system that I am most interested in trying the Fosi ZA3 with balanced connections driving the less efficient KEF LS50 speakers. The Copper accents on the Fosi ought to coordinate well with the Copper-colored drivers on my KEF's. I've ordered some op amps from Fosi Audio to try out as well: - Texas Instruments OPA2134 - Nisshinbo MUSES02 ... show more
Reviewed in the United States on December 30, 2023 by R. Hing

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