Bluetooth Power Amplifier Board with Subwoofer 2.1 Channel 50W×2+100W, 12V-24V Audio Power Amplifier Module with Treble and Bass Control (ZK-MT21)

I was very skeptical about this little amp. Well let me tell you that this thing works great! I read that some said it over heated so I mounted inside of an aluminum box with two fans. I used this amp to reuse my old set of EV speakers. They are a really nice set of speakers with a subwoofer. Well the internal amp went bad so I gutted them and wired them direct. With this little amp they sound better that they did with the original internal amp. The stereo separation is great and the subwoofer kicks way more than it did with the original amp. I just purchased two more of the little amps. I don't know how long it will last but right now this thing works great. I don't know how many watts this thing really puts out but it is quite enough to power most speakers.

this has been in use for a few years as a garage amp. no issues whatsoever, the bluetooth range is acceptable but lacks security (no password required to pair).

I recently picked up a high end powered subwoofer, Klipsch to be exact. Upon getting it home, I found the preamp part didn't work. I got it at a deep discount so the woofer and enclosure was still worth it as long as I found an affordable amp for it. I got looking at single channel amps then I found this one that would replace my existing receiver altogether. It came in and I had an old power supply sitting around that actually plugged right in (12v, if more power is desired you can supply it with 21 or 24 volts, depending on speaker impedance). I was shocked at the output! Even at the lowest voltage powering the device, it's enough to piss off the neighbors. And that high end subwoofer? It sounds like it's powered by the original amp. The power, clarity, and sound definition are all exceptional! I love the separate subwoofer gain and adjustable low pass filter as well. This thing is amazing, not only for the size but also the price. I highly recommend if you can get by without a remote. The Bluetooth works great and is very clear as well. 5 stars!

I bought this to provide a super-simple audio source for my teenage daughter's bedroom. This lil' dude fit the bill. It is no bigger than a sandwich and can be placed in an unobtrusive place. Set up and build was pretty straightforward (I do have electronics experience, so my learning curve may be slightly lower than some) the instructions are a bit hard to follow if that's all you are relying on but doable. And yes, parts and pieces are small to tiny but THAT'S THE POINT. I was able to use slightly thicker gauge, speaker wire by nipping off enough jacket to form a "y" with the naked wire and feed it on either side of the connection set screw, instead of the whole twist being on one side of the set screw. Just be patient. One thing I noticed and this may be more of an issue with the power supply(just bought the recommended) when plugging the PS into the amp, the connector sparks a tiny bit every time IFyou are already supplied A/C from your outlet, plug in the amp side first. It wasn't enough for me to be concerned but rather a condition that probably wouldn't pass UL standards. You be the judge. Amp has sufficient power @4ohms to crank a pair of descent bookshelf sized or smaller speakers. It'll get pretty loud and remain clear till you don't want to go much louder. I wasn't using all that great of speakers but fidelity was fine for it's application. The sub channel was... there. I noodle with the frequency sweep and output to where it was acceptable and sounded OK. Again, I was not using the best sub by a looong stretch, but it was good enough to add and fill some low end to the variety of music she'll be listening to. I/we are satisfied with those unit, but you must TAKE IT FOR WHAT IT IS. We'll see how long gnit lasts, make sure it has some decent ventilation, it does heat up a bit and might thermal protect if it can't breathe a bit.

Works well

Loud and clear! And powers the speakers very well

Update 1/17/2026: Suddenly stopped working. Tried to reset by unplugging. Still not working. Original review for five stars in May 2025. I assembled it and used a laptop 90w charger (20V x 4.5A) as the power supply. I am quite impressed with the sound quality; it is clean and powerful with almost no distortion even when I turned the volume up to a level that might disturb my neighbors (I live in a condo). The amplifier of my Klipsch 10" subwoofer went out. I use this 2.1 amp to power the subwoofer. In addition, it is very small. I'll update my review in a few months if my impression changes.

Surprisingly powerful for it's compact size strong Bluetooth connection and sounds great, has separate volume controls for subwoofer and main volume. Great product, great price and works perfect for my custom built portable party speaker 👌😎

Excelente produto.