No (nontrivial) additive combination of Cs is also an additive combination of Ds (or C#s or Bs or ...). You'd need something nonlinear like multiplicative combi

No (nontrivial) additive combination of Cs is also an additive combination of Ds (or C#s or Bs or ...). You'd need something nonlinear like multiplicative combinations, effectively a C amplitude-modulated by another C, in order to get non-C results.