Embedding strategies currently provide the best compromise between accuracy and computational cost in modeling chemical properties and processes of large and complex systems. In this framework, different methods have been proposed all over the years, from the very popular QM/MM approaches to the more recent and very promising density matrix and density functional embedding techniques. In this paper, we present a further development of the quantum mechanics/extremely localized molecular orbital technique (QM/ELMO) method, a recently proposed multi-scale embedding strategy in which the chemically active region of the investigated system is treated at fully quantum mechanical level, while the rest is described by frozen extremely localized molecular orbitals previously transferred from proper libraries or tailor-made model molecules. In particular, in this work we discuss and assess in detail the extension of the QM/ELMO approach to density functional theory and post Hartree-Fock techniques by evaluating its performances when it is used to describe chemical reactions, bond dissociations and intermolecular interactions. The preliminary test calculations have shown that, in the investigated cases, the new embedding strategy enables to reproduce the results of the corresponding fully quantum mechanical computations within chemical accuracy in almost all the cases, but with a significantly reduced computational cost, especially when correlated post Hartree-Fock strategies are used to the describe the quantum mechanical subsystem. In light of the obtained results, we already envisage the future application of the new correlated QM/ELMO techniques to the investigation of more challenging problems, such as the modeling of enzyme catalysis, the study of excited states of biomolecules, and the refinement of macromolecular X-ray crystal structures.