Fosi Audio M03 Subwoofer Amplifier 200 Watt Mini Mono Audio Amp Full-Frequency and Sub Bass Switchable Amplifier

Wasn't sure what to expect with this little amp, but it really surprised. Using it to power a 8in Yamaha 6ohm passive sub, it put out impressive base that was really well controlled. The crossover worked a treat and I used the volume to set a 'master' gain for the sub as the Fosi ZA3 commanded the system volume.
Overall this was a surprise package in a small system. Driving an 18" in a club maybe not, but in a moderate room with a reasonable passive sub really really good, clean tight base at impressive volumes!
Really my only quibble is the form factor, its really tight for realestate on the back, my interconnects were large (overkill for the set up) and the speaker binding posts are small, I used banana plugs as my stub fingers would struggle to get wires in there!
(note: I have not used this amp in a full range configuration)

Sounds great in sub and full frequency range. Amp sounds clean and is barely warm when running at medium to high power, I am thoroughly impressed.

The power for the size is unbelievable, it is compact but still has enough power to blow most bookshelf speakers. Amp feels solid and well-built with metal knobs. The speaker terminals accept banna plugs and speaker wire which is a nice touch.

One thing to note is that the low pass filter has quite a shallow roll off and you can still hear the muddy lower end of vocals even when set to the lowest setting, I don't find this an issue but just something to be aware of.

dead quiet, cannot hear any distortion, runs cool, ~ideal.

I replaced an Audiosource plate amp with this. The Audisource specs claim 130 watts in bridged mode but my passive subwoofer sounds much better with the M03 despite of the 200W rating being wishful thiunking, esp. with
the power brick it ships with. Consider this amp disposable if you end po not liking it. In that case, you have to pay return shipping to China, which is probably more than the price of the AMP. That is, if you can even get a hold of anybody at Fosi, whihc is , IMO a long shot. i wrote to support complaining about the super-optimistic power rating, nobody ever got back to me, In any case, i actually like the product, it works well for my application. I wish Fosi had some power supply options at the checkout, similar to how they sell the V3. If fthey had a 200W (useable) RMS version, now that woudl be an awesome product