The invention includes a method for controlling amplifier output power in an optical communications network having channel add/drop capability. A first transmission parameter and a second transmission parameter are determined at a first amplifier. In an exemplary embodiment, the first transmission parameter is a composite express signal-to-noise ratio and the second transmission parameter is a composite signal-to-noise ratio. The total output power of a downstream amplifier is adjusted in response to the first transmission parameter and second transmission parameter. A system for implementing the method is also disclosed.