The input signal of the power amp is very simple, that is, the output of the preamp is taken. But the load in the power amp is the horn. The power amp is the load of the pre amp, which is a high impedance load; the horn is the load of the power amp and is a low impedance load.When the preamp is connected to the high-impedance power amp, it mainly provides the appropriate output voltage
Power amplifiers need to be driven by preamplifiers. Its power is generally more than a few hundred watts and used in some professional venues, and the need for multiple amplifiers simultaneously to drive different speakers.Since it does not have a preamplifier circuit, there is no low-level input port, no socket for high-impedance input signals such as a microphone, which needs a preamplifier or mixer to control signal for it.