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 SupplyClimatePartner certified

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.

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.

Seriously good. This little powerhouse isn't just clean sounding, accurate and a true audiophile performer, it is also exceptionally good value if you don't care about brand image and loads of knobs. It is demonstrably better than any other amp I have used that have including 'high end' kit from Quad, Musical Fidelity, Marantz, Cambridge Audio and Sugden to name a few. I'm using 6 ohm speakers and this beauty just sounds exquisitely poised. Depending on the source the mid range is so rich and imaging holographic. I'm now thinking I need to change my (expensive) desktop amp which sounds decidedly 'meh' by comparison, and get another ZA3. The psu and the amp itself gets barely warm in use I am very hopeful that thanks to clever design and high quality components that it will last a very long time. Congratulations to the Fosi team.

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.