A quick Have a look at What you should expect Through Car Audio Built-in amplifiers

Car audio amplifiers are primarily used to convert a signal from a source unit and change it to a higher level from a lower level to drive the loudspeakers. These amplifiers are available in various models that can range from a lowly 20 watts per channel to more than 1000 watts per channel. Furthermore, the price too will vary according to the power of the amplifier and can range from a paltry 50 dollars to well over one thousand dollars. The price you end up paying will depend on the features

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