The amplifier circuit using TDA7851L 4 channel audio amplifier IC. This IC can able to deliver 48 watts per channel. The main advantage of this IC is about the working, the 12V single supply is enough to drive the Amplifier circuit. This this IC is the best choice for the Car audio amplifier circuit.
TDA7158L IC 4 Channel Amplifier Circuit
The inpuit section of the IC is marked as IN1,IN2,IN3 and IN4. You can connect the 4 channel pre amplifier section here to get the perfect output voice through the amplifier IC.
NE5532 4 Channel Preamp circuit
The above NE5532 IC based pre amplifier circuit is consist of summing of Left and Right channel from the USB module to get the rear speaker audio signals. Also a 7805 5 v regulator IC is attached with this, to power the USB module. All grounnd of the circuit is connected to the Vehicle chass or body.