We show how to resolve coherent low-energy features embedded in a broad hig
h-energy background by use of a fully self-consistent calculation for compo
site particle operators. The method generalizes the formulation of Roth, wh
ich linearizes the dynamics of composite operators at any energy scale. Sel
f-consistent equations are derived and analyzed in the case of the single-i
mpurity SU(N) Kondo model.