In such devices, small stereo amplifier ICs are installed from reputable manufacturers, which I will not mention here for legal reasons. This amplifier IC's are also found in car stereos, televisions, mini and micro systems and usually afford little more than real 10-35 W RMS per channel, with a maximum allowable speaker impedance of 4 ohms. They are not 2-ohm stable, because the Class H amplifier IC's work primarily in BTL mode.
They have usually also overload and overheating protection.
The efficiency is very bad, due to the power supply: A proper power amplifier utilizes a symmetric DC power supply, the positive and negative voltages of about + -50V has to signal ground.
For small applications, eg as an amplifier for PC music applications instead of computer speakers, they are ideally suited. But even on the barbecue as a cell phone, or MP3 Player Amplifier, as well as an additional amplifier in your car, caravan, boat, or motorcycle you can use them.
The 3 star deduction is due to the high price of 98 and the misleading power rating, which give many buyers believe and do not know how to be in reality, according to real 400 watts.
The equipment value should normally be no more than 20-30 euros.
If the unit is operated through an AC adapter, so I recommend one that provides a stabilized output voltage available. Otherwise, annoying humming noises come from the speakers.
