The amplifier 4000.1D from the company DB allows for increasing the power of the car speakers. It is a device that amplifies the electrical signal received from the car's audio system and transfers it to the speakers for playback. It is a monophonic amplifier which means it can power up to one subwoofer. It belongs to the category of class D digital amplifiers which have high performance, high power, and low consumption. Its power is 2000W, so the speakers you choose should have corresponding characteristics to have clear and powerful sound.