Embodiments are directed to an apparatus, method and system for relative or absolute equalization of two or more channels. The apparatus includes a receiver that receives a variable-envelope signal, a self-consistent outphasing separator that splits the received variable-envelope signal into constant-envelope signals, and linear pre-equalizers that equalize the constant-envelope signals relative to each other or to some target. The apparatus also includes an analog combiner that combines the constant-envelope signals, and a feedback loop with a processor that receives the combined constant-envelope signals as inputs, analyzes the combined constant-envelope signals to identify pre-equalization inputs that, when applied to the linear pre-equalizers, will equalize the constant-envelope signals, and provide the identified pre-equalization inputs to the linear pre-equalizers, so that the combined constant-envelope signals are equalized relative to each other or to some target. Adaptive algorithms use a dedicated calibration signal, regularly transmitted (data) signal or combination of the two.