For it`s maximum result, the final stage of the amplifier should have the proper power supply, as the flowing, currents are very high. An Class A amplifier, requires attention. These are the rules for the power supply for the Class A audio amplifier. The transformer must be able to provide the required current at any time. The amplifier requires high current at stand by, the filtering capacitors have enough capacity, so they can supply enough capacity, so they can supply enough current whenever we need it.