Here I will explain about the necessary voltage and power amplifier output. The voltage should have at least approximately 9Volt 30Volt voltage and maximum voltage on the DC current. For maximum output of 2 X 2Watt with impedance 8-16 ohm. Because this amplifier circuit using ic and ic is used have the equation, so that if used different ic, then the required output voltage and also differ depending ic respectively. Part List : Resistor R1 = 1M R2 = 1M R3 = 1K R4 = 1K R5 = 100K R6 = 100K R7 = 1R R8 = 1R Capacitor C1 = 1uF C2 = 220uF C3 = 1uF C4 = 100uF C5 = 5uF C6 = 5uF C7 = 0.1uF C8 = 220uF C9 = 220uF C10 = 0.1uF IC U1 = ULN2274B , ULN2277 , ULN2278B