Bluetooth Power Amplifier Board Stereo - HiFi 2.1 Channel 2X220W+350W Bluetooth 5.1 16-32V Digital Power Audio Amplifier Module Subwoofer Control with AUX/Bluetooth/USB Flash Drive (ZK-AS21)

Bought this amp to run my open but roofed outdoor ‘cook porch’ sound system. Was using a smaller amp from the same manufacturer; Wuzhi Audio, (MT21), for a year or so, which is good for 50 watts a side into the main speakers, and 100 watts into the subwoofer. (Do an Amazon search on Wuzhi MT21, I tried to do a link, but it came out as crazy long jibberish!)That one worked well, and when I saw this higher powered version, decided to go for it. Both are fed by high current power supplies with plug in speaker pigtails so I can A/B swap them easily. The original reason for the quick disconnect wiring was so the amp and power supply could be removed and stored indoors when not being used, and it made sense wiring the newer one as a ‘drop in’ replacement.As a result, it gave me the ability to do a quick comparison between the two amps.The larger amp has additional inputs in addition to the higher power rating, and the power input has a hard wire terminal strip instead of only the somewhat flimsy small power socket that is supplied with the smaller amp. This would be my only complaint about the smaller amp.Overall the larger amp is a much more robust build, both in power and chassis/component build.As mentioned earlier, the small amp worked well, with clean power delivery throughout its volume range. It is designed to simply not go any louder when turned up beyond its limits, and never clips or distorts.The larger amp shares this functionality and performs extremely well. They both feature the power switch as part of the volume control, which helps prevent turn-on into a volume level left high from a previous listening session. It’s an appreciated design!Have only used them on Bluetooth, which works very well. They connect quickly, are stable, and have decent range. Have used them with an iPhone, iPad, and android tablets with no issues. Have yet to try the USB or AUX input on the higher powered amp.The crossover is smooth and linear, and the separate subwoofer volume control allows balancing the subwoofer level to the main speakers. The bass and treble controls have good range, but I find leaving them at their midpoint works well. At least the ability is there if you need some tweaking to fit your listening environment.For reference, my musical taste is new/old country, classic rock and R & B. I enjoy some volume, but do not punish my speakers or my ears!In my application, the main speakers are 8 ohm, and the subwoofer is 4 ohm, so the amp output is lower than its advertised capability, (specified at 2 ohms), but is everything I need. The output power is roughly double that of the smaller amp, and is most discernible where it drives the subwoofer. As the higher powered amp has an on board cooling fan for the output components, it’s chassis runs cooler than the smaller amp at the same listening levels. Likely also a function of more headroom at the running power output.Kinda toying with the idea of adding a ‘shaker’ module to the porch floor frame to add some ‘butt shaking’ to the audio experience . If that happens, will add my observations to the review. 😏This review inadvertently turned into one for both the small and larger amps, as the smaller one is my point of reference for these little amps. Being an old audio engineer, I am really impressed what can be done with such a small package. Both are extremely good for their price points, with more power and features available for the larger one.Of note: In order to get the full performance out of the amps, you need appropriate power supplies. “Wall warts” are NOT valid here! The manufacturer does state this in their published specifications .Today’s switcher power supplies are reasonably priced, and have robust clean output power.For the smaller amp, I use a 24vdc @ 15amps, (360 watts) supply.(https://www.amazon.com/dp/B06XK2ZNKC?psc=1&ref=ppx_yo2ov_dt_b_product_details)The larger amp is powered by a 36vdc @ 27.2 amps, (1000 watts) supply. (https://www.amazon.com/dp/B0C5DPSFZG?psc=1&ref=ppx_yo2ov_dt_b_product_details)While the price of the amps is good, consideration must be given to the add on cost of the necessary power supply.As a side note; during a multi day hurricane induced power outage, ran the smaller amp off of a Ryobi 18v 6AH battery, and it sounded great. As this amp is no longer being used on my ‘cook porch’, thinking of doing a project build of a portable Bluetooth ‘boom box’. Yeah, there are lots of commercial ones out there, but a 2.1 version with superior power and speaker size, using a swappable battery would be a fun thing to do, for me anyway! Such is the life of an old retired engineer……..

I bought this and used it for a day and had to return it because it died. Did are turn and bought it again and have been rocking out with it since,been about a month and I love it.I have it powering a pair of jvc bookshelf speakers.The speakers are rated at 3 ohms probably 200 watt capable easy.I have a 8" sub offer on the unit rated 3 ohms 600 watt capable.These speakers were purchaced at a yard sale but are of godd quality for sure.I connected the to the unit and was very impressed with the sound,the sub hits hard and loud,I get the drums and bass that just blows me away,the bookshelf jvc speakers also are a very good fit and just rock out way better then I could have imagined.The controls are easy to figure out also,bass and treble are adjustable for the bookshelf speakers to suit me needs and adjustment for my sub is aslo impressive. This is a great product for the size of it and I'd also say I haven't used the other features this thing has to offer but I'm sure it all will be goodI gave it 5 stars for the sound and it's quality build.Overall great product.I'd buy it again if this ever fails because if you are like me,I love my music loud!Quality sound for it being the size that it is, I'm impressed. My only con is trying to find a proper power cable for the amp itself,if anyone can guide me to one that would be great. As for now I'm using Alitov 110 volt power output 36 volt 4 amp 144 watt power adapter. So far it works good but not for sure if it the correct power source for this. Had trouble finding this power supply online but it's been working so far. I'd like to find something better and if someone can point me to it that would be great.Great product though,I love this thing and would definitely but it again if it ever craps out on me.

I will say that this product was was a dud.. didn't never get any sound out of it. but the bluetooth and other connections were not any problem just had sound issues...

The amp's circuit board is well assembled. Everything is very clearly labeled. But it needs an owner's manual that explains the dial wheel functions as well as what the sub frequency knob does. Is it an adjustable low pass filter? 20hz-20khz isn't much of an explanation. A sub-sonic filter to attenuate frequencies below the subwoofer's lower frequency capabilities. But over all, a great product for the price.

Built several radios with this works great

I used my laptop adapter to test the output quality but not enough to power to get the true impact, the bass sounds good but at a low volume. The power supply is the culprit in this scenario and if the manufacturers could redeem only themselves with a power supply I will keep it.

That u have to assemble the box rather than selling it closed in already

With the right power supply this little amp can put out more power than it is advertising. It is a surprisingly capable little box. I recently bought a higher amperage power supply for this (36v & 10amps, the max it is rated for) because the previous power supply I had (36v, 2amp) couldn't power my 8" subwoofer at full volume which would result in the amp shutting itself off (a safety feature). The subwoofer is rated for 400 watts RMS, 800 watts peak. With the 10amp power supply this amplifier was able to completely destroy my 8" sub, which I was rather impressed by considering the rated output for the sub channel is only 350w. I have since ordered a 10" sub since I clearly have some headroom on the sub power. This is actually the second one of these amps I'm purchasing, I just like them that much.