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

So I ordered this because I wanted too, that simple. I’ve been looking at these small amps from a distance land and I figured there’s no way they can sound even half decent but I was wrong. Curiosity got me I guess, so on with my opinion.Setup for my testing was simple, connected a Marantz SA8005 disc player, fantastic DAC it has, then tried two different sets of bookshelf speakers I had laying around. Went back n forth a few times as my son assisted (musician) due to my ears being old. First was a vintage set of JBL LX22’s and although these speakers are easy to drive they can be fatiguing at high levels and they were. Next was another bookshelf, KEF q300’s, yes 300’s not 350’s. Both speakers are a bit bright but my Marting Logan 35 XT were being borrowed so I used the above mentioned. JBL’s too harsh and oddly they seamed weak. Japanese amps seem to be better with them as they were harsh with my NAD 356bee as well so KEF it is.Sound stage is there and the amp is fairly detailed but for $150 it is so much better than expected. At first when I picked it up out of the box it felt so light I was concerned. But I’m used to different equipment. I’m more impressed with vocals as usual that is where cheap crap just can’t hold a candle and this little thing does that well. Highs are ok, a little lacking in detail but very very close to my NAD. Bass, actually is good, as I’m listening now. It has punch, it’s not to slow and it doesn’t breakup. I put a 10” sub and even better. Not much it’s lacking at this price range at all.Pros, unbelievable at this price. Using the 48v power supply, I’d say it compares to a 60 to 80 watts per channel amp. But the bass punch exceeds that. May get another and mono block them and when my headphone amp comes back I will use that DAC with XLR cables to see how hard I can push the KEF’s. Also this is extremely quiet, no noise at all.Cons, binding posts are cheap, holes don’t fit big cable that I use, you can use banana plugs, I don’t as I like raw wire so that I found a bit irritating.I’m set up temporarily in a 11by 16 room that isn’t a great room for sound so who knows what it sounds like in a better fitted room but again I love this little amp and I’d say you can’t go wrong at this price or even double. I can go on n on detailing different instruments, imaging , etc but no need just buy it.Not sure if this technology needs a break in period so maybe it will get even better. One more note, as I’m writing we’re testing this out and I hate to say it but the bass is better on this than my NAD but I’m going to have to get that and do a comparison as if it is then I’m sold.Update: after about 20 hours of break in it got better. More sound stage and the bass tightened up. I picked up another to run both in mono. The only noticeable difference was more lower end, and I actually shut off my sub. The sound stage was different but not better or worst after I ran both all weekend. What I did do was remove all unused opamps from both units leaving only the right ones in both. This actually made a slight improvement and cost nothing. The soundstage opened up more and gave it more depth. Everyone’s ears are different and then factor in the room and other equipment you have, so you may get different results or none at all however, the Za3 is amazing. I may order some opamps to roll for fun. But for now I’m going to leave as is as I want to settle in to the sound they produce before I change anything else so I’ll have a better chance at hearing any changes.Update2: I added a Bluesound Node for streaming and as a preamp. Now I can not only adjust the volume from the bluesound app but I can adjust both at same time leaving both za3 knobs set. Also the node has a sub out and has crossover adjustments so this completely changed the game.That plus tone controls on the node have taken these to the next level. Best $300 bucks I ever spent. My son said the soundstage is something he didn’t expect and said it’s better than the NAD Amps we compared this too which shocked us both.

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.