Review on Douk Audio Amplifier Subwoofer Full Frequency by Kevin Abner

This device has noticeable sound distortion to the naked ear. I replaced the included lamp with a GE lamp and the distortion hasn't decreased. I connected the unit to a tone generator and connected the output to a non-inductive load connected to an oscilloscope. The oscilloscope did what I heard, distortion well above the advertised 0.1%. I haven't hooked it up to an audio distortion analyzer for the exact percentage, but it needs around 10% distortion to be noticeable to the unaided ear. I bought a second one and the result was the same. When you present an audio file, this device is not satisfactory for your ear.