Car Speakers & Audio Equipment
The Easiest way to improve the quality of audio in your car is to improve your speakers. Standard factory fitted speakers usually only provide between 5w & 20w peak output & usually made from inferior substandard materials. The materials used are prone to distort and whine when the power supplied is turned up. Considering that most Factory head-units (stereos) only supply an amplified power signal of up to 20w, you can see that the speakers are very quickly at the maximum level.
Aftermarket Speakers are usually between 50w RMS to 250w RMS (400w Peak), instantly providing the extra quality needed. Although the Power output is not the only guide to how good the speakers are, it is a good indication to how the speakers will handle the power provided and reproduce into a good output.
Depending on the level, quality and volume wanted or required, factory head-units may not be able to reproduce the signal to a powerful enough level. This is only usually the case when building a whole system involving Amps & Subs, in which case you would need either an aftermarket stereo or a line-driver.