This parameter determines how much power — measured in watts (W) — a speaker can handle. If you have a low-power system, the speakers won’t have to handle the high input power. On the other hand, a system with powerful external amplifiers will require speakers whose output power is close to that of the amplifier. A good rule of thumb is that the power of the car speakers should be 1.5 times greater than that of the amplifier.
Also, keep in mind that the most important parameter in this case is the maximum RMS (root mean square) power, not the maximum peak power. RMS determines how much power a speaker can handle continuously, not just short peaks. A system with a power rating of 2 to 50 W RMS will be better suited for low-power stereo than a system with a power rating of 10 to 80 W RMS.
Car Speaker Sensitivity – Sensitivity determines the amount of sound a car speaker produces from the power applied to it. If you have a low-power car stereo (15 watts RMS per channel or less) — which is standard in most cars — speakers with high sensitivity (above 90 dB) are a great option. However, if you have a high-power system (16 watts RMS per channel or more), consider speakers with lower sensitivity. With the proper power, they will provide excellent sound quality.