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

Fosi Audio's best amp in my book, especially when paired with the ZD3 as I have it for my desk top system. Superb value for the money, I still can't believe how cheap it was and still is. The amp drives every speaker I have with absolute ease!! Great sound stage as well. Just a fantastic bit of kit as they say, TOP MARKS Fosi A Further UPDATE, as I have now purchased a second ZA3, I've been so impressed with the first one in 'Stereo', I thought it would be rude not try the ZA3's in 'Mono' so required a second ZA3. Boy oh boy, this set up is just fantastic, the sources are CD via coaxial, Laptop via USB, mobile phone via B/T for streaming. All three through the ZD3, acting as DAC & Preamp, with the ZA3's working in 'Mono'. I can't believe how much better everything sounds, more defined instrumentation, cleaner sounding mid range and treble, with a more powerful bass punch, with an even wider soundstage. Absolutely amazing, completely blown away, and I'd say this little set-up, drives my floor standing speakers just as well as my Cambridge Audio CXA81 MkII integrated amp does, for half the price. Now contemplating on the purchase of the ZP3 to act as pre-amp, with the ZD3 as DAC only, so I can incorporate my T/T into this 'little' combo.

So...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.

After much thought, I purchased two of these Amps to work in conjunction with the Fosi DAC ZD3 that I had previously purchased. I have both Amps set up in Mono to the DAC. The DAC does the channel separation. I have not lived with the system for very long, but initial impressions are that these are incredibly good amplifiers that really punch out good clear sound. They are also now possibly exposing the weakness of my speakers, but that could also be just another head rouse to purchase a different set of speakers. I like the fact that I can later play around with Op Amps, and that will take my Hi-Fi hobby into another dimension. I did have a little trouble setting up the triggers to both Amps, but that was easily overcome by purchasing a 3.5mm male jack headphone splitter that goes into two 3.5mm female ends. I have then added two short 3.5mm male to male cables to go from the DAC (now doubled) trigger to the amps. It works perfectly and the trigger does not seem to mind a double (stereo) 3.5mm lead for it to work. CEC works brilliantly on the DAC, so I can now turn on the whole set up from my smart television. The television is hooked up to the DAC via eArc HDMI, so a digital signal is received at the Fosi DAC, which is in turn doing all the heavy lifting to convert sound to an analogue signal, which it passes to the Amps. The Amps are turned on by the 12v triggers rather than the CEC signal.

Second 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.

These are an amazing amp for the money. There’s plenty of reviews on YouTube comparing them to £7000 amps they are that good. Brilliant as a stereo amp and even better as a pair set in mono connected via xlr. Great paired up the pre amp ZD3 if you’ve using a streamer or CD player as source. Ignore the audiophile snobs and the lack of reviews on sites like what hi-fi that depend on pushing big names to fund their site. What’s even better is you can crack these amps open and swap out the opamp chips for even better performance. There’s so much power in these that you could easily power big 100w speakers as well as 30W book shelf speakers. Sleek and clean look small in size so two fit nicely side by side. Easy to connect put blistering performance for the money. Only sight negative if used in mono it lowers the subwoofer volume . So you may need to up the gain to compensate.

Excellent. Originally used with a q6 dac feed via USB from a laptop and p4 preamp to a pair of wharfdale lintons. Swapped q6 and p4 for a topping velvet and the difference is tremendous. The za3 easily powers my wharfdales way beyond volumes I would need to get myself evicted. No hum , no noise whatsoever and great clarity and seperation. Incredibly clear. Now fed with the topping I have a stunning system

I bought this amp after reading reviews online so I shouldn’t have been surprised by how good it is but I was. Firstly the size, it is small, I wanted something for music in the bedroom and this is small and discreet which it is. My second surprise was the power it delivers from such a small size. I’m driving two mission towers and a kef sub and this sounds awesome. It’s not a fancy do everything amp but if you want good power without breaking the bank I’m not sure why you would look any further. I’m very happy with it.

Bought a pair to use experimentally as mono-blocks with a home theater receiver. To be honest I can't tell the difference between the Marantz receivers Class A/B power amps and the pair of ZA3's. However use of mono-blocks with the Marantz FL/FR pre-out guarantees power to Front Left/Right DALI Oberon 5 speakers and the receiver runs a little cooler. I particularly liked that the ZA3 pair can be power controlled by the Marantz via the 12V trigger out. Without the trigger input the ZA3 pair would need to be manually turned on/off - not ideal for my application. The trigger input is necessary because there is no physical power switch, the trigger input bypasses the less than optimal "push and hold the volume knob for 2secs" to turn power on/off. I just set the volume to max on both ZA3s and the receiver controls the volume - there is no hiss. Actually I adjusted the left channel down slightly to balance the sound when listening to Vinyl/CD in "Direct" mode via the Marantz. In Home Theater sourround sound modes the Marantz Audyssey room correction will I hope compensate for the slight difference in volume levels between the two front channels - assuming that the Audyssey setup was run after the Analog balance was set for Vinyl. However be aware that using a mono 3.5mm male/male jack plug for the trigger connections (via a 5way stereo adapter) will short the 12V Trigger out on a receiver. Using stereo jack cables should be OK but I did not have any male to male 3.5mm jacks so I took the ZA3 apart and found and cut the offending link on the trigger input. The link connects the inner ring on the jack to the tip (12V) so a mono jack just shorts the 12V tip (via inner ring) to the rear ring (GND/0v). Build quality seems excellent otherwise.

Zakupiony do współpracy z Wiim Ultra, spisuje się doskonale. Opcja trigger działa idealnie, wzmacniacz włącza się razem ze stramerem. Bardzo dobra jakość dźwięku. Bez problemu napędza kolumny zarówno podstawkowe jak i podłogowe. Szczerze polecam!

A critical part of what is becoming a very beautiful sounding system. I have an older set of kliptsch tower speakers and sub. This amp(s) drives sound that is clean and true. I have since purchased another ZA3 and am driving them in mono mode. Very good quality Very user friendly Very highly recommended

where to begin! My previous setup was Marantz PM6007 with WiiM Ultra & Elipson Planet L Speakers. I was ok with the setup but I knew, was missing something on the higher frequencies & details. just heard about this product on youtube channel "VirtualHiFi" - found many good videos with sound test comparing with 10k - 15k USD costing amps. I took the decision & bought this today with 48V power supply & right now its been playing for 3 hours replacing the marantz PM6007 only with rest of the same setup. I have no words to say - Man! it's blown away the marantz right out of the box and my elipson planet L speakers have come to life. it's a night & day difference. I kept the volume at 75% position & controlling the volume from wiim ultra and it's running cooler now than at 100% position. i am seriously thinking about the reason why it is sounding great than the marantz. Hmm.. may be one reason - the frequency range with 0.1+-DB? I don't know but it's sounding fuller, detailed, airy high-frequencies & analogue kind of texture. ZA3 changed my mind to join in the class D era as I have ordered another now to try as Monoblocks. I am totally happy & the value for money is top of the roof! I really appreciate the FOSI TEAM behind this to design such a great product! Best of luck for your next musical invention!!! Got the second one & set them as monoblocks - sound stage is wider now & details are more cleaner especially the vocals & mid range. I started enjoying my setup now with peace of mind!

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....

Klinkt echt prima. Aanrader. Werd ook tijdens een hittegolf nauwelijks warm.