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

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. 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.

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.

Hi. 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 expectationsCheersQuick 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.

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.

This 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.