The pure post-amp amplifier is a simple volume expansion, which requires the expansion and control of the pre-amplifier. Pure post-amplifier only needs the amplifier part. It is convenient to deploy with all kinds of fronts, and there is a large space for promotion. The preamplifier with preamplifier is a complete amplifier that combines the pre-stage and the amplifier stage in one combination. Generally, the amplifier generally has a 20 decibel preamp expansion or tone, volume, etc., and has multiple sets of inputs; The pure post-amplifier is only used for power expansion, at most only with volume adjustment, and the input is generally 1-2 groups.

It can be said that the front level makes a voice, the back level contributes, the front level is the leader, and the back level is the bottom. You don't have to preamp in fact, you can, you can also install a volume potentiometer to control the volume, but adding the preamp is not only used to control the volume, but the effect will be worse under the same conditions, the input impedance of the amplifier amplifier is difficult to say that it is completely matched with the sound source, the input impedance of the amplifier is often too small, and some audio sources can't advance the power amplifier, so it is necessary to use the preamp to do impedance matching.

Others can participate in the pitch circuit in the preamp, make the tuning preamp, participate in the expansion circuit, do the preamp expansion and so on. Preamp is not necessary, but manufacturers add preamp in order to match various audio sources. AV amplifier matching is one reason, and the other is to integrate tone, input selection, and singing amplifier in the amplifier, and participate in the preamplifier of multiple functions. There are also a small number of uses to meet the special needs of some people, such as gall pre-amp "polishing", tone circuits, electronic frequency division, etc.