First of all: the power amplifier (host), the rated power generally refers to the continuous output of the RMS (RMS) power; the speaker, the rated power known as the speaker can bear this value for a long time without damage, The need for such a high power amplifier was forced to move, but not necessarily to the amplifier (host) "to obtain" such a large electric power.
The driving of the car horn is mainly determined by its sensitivity and impedance characteristics. Nor does it mean that the amplifier can not be equipped with a power greater than the rated power of the speaker. Just as driving a car, driving a 300 km speed car does not mean that there will be a car accident, you can not open so fast. Similarly, as long as the volume is not blindly increased, high power amplifier can be equipped with low-power car speakers. General host rated load of 4 ohms, as long as the car horn impedance is not less than 4 ohms, the host volume knob does not open to very large, even if your horn power is 1 kW will not burn the host.
The second, in addition to considering the car horn and host matching degree, the power amplifier needs much?
General single amplifier are better, marked are authentic RMS power, that is, the maximum distortion is not true sine wave power, referred to as the root mean square power. This power indicates that the power amplifier distortion does not exceed the target value, the long-term output of such a large power.Looks less power amplifier, such as 2 × 50W, 2 × 60W, working up with a mold like. The power requirements discussed below refer to RMS power, and it is important to see the "RMS" or "maximum distortion-free" power when buying the amplifier. The other signs (such as music peak power, maximum power) are actually divided by 2 or divided by 10,20 to be equal to RMS. For the amplifier, the rated power generally refers to the effective output (RMS) power that can be continuously output; for speakers, the rated power is known to mean that the loudspeaker can withstand this value for long periods of time without damage, which does not mean that Power amplifier was forced to move, car speaker drive is mainly due to its sensitivity and impedance characteristics to decide.