The amplifier GZPA 4SQ from the company Ground Zero 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 four-channel amplifier which means it can power up to four speakers. It belongs to the category of class A/B analog amplifiers which provide high quality, low performance, and low power. Its power is 125W, so the speakers you choose should have corresponding characteristics to have clear and powerful sound.