Review on Velleman K4001 Mono Audio Amplifier by Patrick Reid

Good quality kit. Extremely light and easy to assemble. A good set for beginners, for those learning soldering. The output level is loud, there is no distortion. The only reason I didn't give it five stars is that there is noticeable background hiss when the volume control is set to the minimum. This made it impossible to do what I wanted to do, which was to boost the extra speaker for the radio. Even turning down the volume to listen to other radio stations couldn't get rid of the annoying background hiss. I couldn't find anything wrong with the assembly or kit components and battery powered both the K4001 and its audio input source to eliminate any noise or hum from AC sources that switch or rectify DC. I don't know if protection is required but the instructions don't mention it.