ZK-AS21 220W*2+350W 2.1 Bluetooth Power Amplifier Board with TPA3255 Chip, 18V-36V Bluetooth Speaker Audio Amplifier Module Vehicle Amplifiers

EDIT:: 1 month (ish) into owning ::: Still unreasonably impressive. Will probably report again in another 3 months. Been using it constantly, hours every day. It's protection circuits function properly too, it easily survived a fairly catastrophic failure of a 360w switching DC power supply. (Was fireworks)Im blown away every time i turn this thing on. Fantastic choice in filtering capacitors as well, they burned in very nicely. The sound quality of this amp is, in my opinion, superior to my yamaha s801 at all listenable volume levels. It's almost painful to say it, but it's the truth.Post burn-in with a properly tuned set of speakers and a sub, this is reference quality sound 100%. I cannot even begin to fathom what may be possible in class D in another 10 years. Pretty sure i could be quoted in saying "it's not possible for class d to be as clean aas class a/b, let alone class A"Yea, well, if you don't think class D will, and some day quite soon, be the indisputable king of amplification technology, you just simply do not understand how this kind of technology evolves and progresses.Ive had Zero issues, the reviews that mention power cycling, yea they have a bluetooth device auto connecting killing their analog audio feed. BT gets first priority with this amp, always check your bluetooth devices if you are facing this issue. Anyone who says this amp does not provide enough power are definitely using a sub standard power supply. Im running it at about 600 watts on 36v now, and it can shake the walls long before it starts to distort. The detail and high frequency clarity, makes the yamaha (no slouch at all) seem blurry by comparison. The difference is subtle, but once noticed makes ya step back, and say WOW.I am not going easy on this thing either, i push it hard, and i push it often. Another big benefit i've noticed, is my listening space doesn't slowly get hotter as i listen at volume.I will probably be purchasing a fosi audio bt30d pro to replace the yamaha in the living room, and this whuzi amp will be living on my desk for the foreseeable for mix referencing.ORIGINAL REVIEW:::Packaging was adequate, unit arrived in one piece of works as expected to. Really, it's one of the most impressive peices of audio equipment, for the money, that i've ever come across.I cannot speak for the reliability of this amp yet, however... Running it from a 36v 11a switching DC power supply with a dc noise reducer between the amp and power supply, I am unreasonably impressed. The power output, and sound quality is phenomenal, and it compares favorably to a yamaha s801 reciever when it moderate and low volumes. Will make a perfect far field reference amp when i switch off the near field monitors and step back. And i can finally stop going back and forth to another room when i want to reference how some changes in a mix will translate to a fully fledged stereo image.Paired up with some re-invigored vintage Acoustic Research series 660 far field monitors outfitted with Dayton reference drivers and GRS Ribbons and a dayton reference 10" HO sub in a sealed/braced 1cuft enclosure.Had previously tried out dajunguo's tda7948 2.1 offering, and it sounded good, very listenable, but it made my tweeters have a strange resonance, and as fragile as ribbons are that's a no go in my mind. I gave that amp away. Did some research and determined the tpa3255 chipset to be what i was really after, and it was.At moderate volumes (definitely not quiet) with an adequate power supply, this amp has more output then ill ever need for the intended purpose, and it's sound quality is far beyond what i expected. The stereo image extends out beyond the drivers in every direction. The articulation and detail is FAR beyond its price point. And the low end response is more present, powerful, smoother, tighter, and somehow more open then the dayton amp i was using in conjuction with the yamaha s801.The mid range detail, and high end clarity and imaging accuracy is absolutely on par with the s801, the yamaha pulls away pretty handily at loud volumes though. But it's also not powering a passive subwoofer on its own, so that should be that way.Im sure the yamaha will still be serving someone the desired purpose in 20 years. This amp will probably be long since dead. However, you can buy 16 of these for the cost of the yamaha.In my opinion, that favors this little guy pretty handily for anyone who cant really eat a large purchase, which is many, many people now a days. If it lasts more then a year, then the Yamaha actually loses the comparison on all fronts in my head. Anyone who doesn't think class D *will*, and one day soon, be the reigning king of amplification technology, just has no idea how digital technology actually works, or evolves. I hope it stays working well, because it scares me every time i move that heavy yamaha and power it back on. But i feel like i can literally toss this thing around, and it can fit in a handbag pocket.

Bought this to replace a set of computer speakers I had in my garage and am really happy with it. I bought a 36v power supply for 15 dollars to run it, though I honestly didn't need to since I already had a couple ac adapters around that push 19v at 4.5amp and when tested they pushed this amp more than needed. The 36v power supply definitely upped the power though, only noticable in the subwoofer, and was worth it to me. Sound clarity is really good. Even with only being able to adjust the volume and frequency of the sub channel and the treble and bass of the speakers I was able to get this amp to sound great.....even before trying to mess with the equalizer on my Bluetooth source. Honestly this amp was able to produce clear non distorted bass no matter what the song, something my car with JBL and Infinity speakers cannot do, and at full volume crystal clear vocals and treble out of the two tower speakers. Bluetooth hooks up really quickly once paired and is pretty hassle free. With that I decided to make a garage stereo out of an unused cigar box that I had lying around and so far everyone that's taken a look at it has said they love it. Overall it was a fun project that I could do with my son and now I have a really decent to great stereo for summer driveway fires or working on cars in the garage. Cheers!P.s. I actually considered doing a hidden stereo build with this amp for a super clean look with the floating shelf since it's so small. Like stick it underneath the floating shelf and all the way back against the wall or hidden in a tool drawer, but decided I wanted to show this off. Also the cigae box allows me to close the lid and keep garage dust out. So in the end that's what won.

Works great

Board was simple to assemble and use. Bluetooth can connect to phone without the app. Using the amp with a 36vdc 6 amp power supply which is good for the moderately low RMS of the drivers (Dayton Audio SD270A-88 subwoofer, 80w RMS @4 ohms, Dayton Audio ND140-8 mid bass, 40w RMS @8 ohms, Dayton Audio Mini-8 Air Motion Transformer, 15w RMS @8 ohms).Sound is excellent, tone controls, sub freq, volume controls work well but, if you have a song that hits hard from the beginning, e.g., Rush's Tom Sawyer, that initial kick drum/crash cymbal isn't heard.

Unit for bluetooth work's great but it's software for my android does not work at all. So I now they need to go back an fix there software.

Good bang for the buck I'm running 2-(80w rms) bookshelf speakers and 100 watt RMS subwoofer sounds really good off the 3.5 mm auxiliary cord coming from the back of the TV I don't have a oscilloscope or anything to test it ,to that extent but I don't think it's pushing out what's advertised for Watts but it does stress my speakers if I have it up too loud.. I am running a 19 volt 3.5 amp power supply.. I recommend a 24 -36volt 5 amp power supply ... if you want to make a portable Bluetooth power speaker you can run it off a drill battery or any battery up to 38volts I recommend 36 volts max or 16v min.. does work on 4s-(18650) batterys.. a typical drill has 5s(20v).. if you want to make a portable sound unit with it I recommend a 2P-4P, 8s(18650) pack... Note for example (2.0 ah Craftsman battery is a 1P, 5S.. a 4.0ah Craftsman battery is a 1P, 5s (P usually equals out to parallel cells and s equals out to cells in series)... Anyway all in all works good

Sound was good, Power was weird because every time I plugged it in, it would spark

Completely Underestimated this unit! I've been using it for more than a year now. I've got it playing through 2- 6x9's and a 7" sub. I can only turn it up half way without feeling like something is going to explode along with my eardrums lol. I get a minimum Bluetooth range of about 75' ft! I have more improvements to make on this current build but it's still perfect!