What is the difference between 2 channel and 4 channel car amplifier

Alleged double channel power amplifier, it is built in two independent power put circuit, call R, L(left, right) channel,
of course, audio input and preamplifier circuit also are independent separate, left channel audio input signal R,
the output after the internal independent preamplifier and low frequency drive left channel sound box.
Right channel audio input signal L, internal independent pre and low frequency amplification after the output drive right channel speaker,
we usually put R and L channel input and output, collectively known as the dual channel.

One, four channel is relative to two channel. Four channel, is the two channel stereo in more than one way output, is 4 channel.
That's two channels of stereo output. The four-channel has four articulation points: front left, front right, back left, back right,
and the listener is surrounded in between. So, who manages the quadrophonic channel?
It is managed by a power amplifier (that is, an amplifier with a knob on the dashboard).
Four-channel amplifiers can be used with 4 horns, or 6 horns or more.
In terms of the overall effect, the four-channel system allows you to surround sounds in many different directions,
giving you the feeling of being in a variety of different environments. Its sound quality is superior to two - channel stereo.
Figuratively speaking, a four-channel is equivalent to a highway, which can drive four cars in both directions,
while a two-channel is only equivalent to an ordinary highway, which can drive two cars in both directions.