Today, the sources of electronic and mixed music produced in the XXth century by analog means have entered the digital documentary domain. Therefore, the theoretical reflection on the ethics of preservation, restoration and re-issue of audiovisual documents cannot ignore the models of communication engineering: encodeing and decoding, audio signal processing – also implemented in the World Wide Web today – are of paramount importance. After World War II, a new musical research was born within the context of acoustical and electro-acoustical communication systems and it found a privileged thread in the Theory of Information. In the world of electronic and mixed music the technological system is an integral part of the compositional project, and the audio tracks represent a ‘projection’ of the production project. Audio recordings deliver to the editor an essential evidence for reconstructing the technical and theoretical world of the composers, which is to say their pre-post-history. In this paper, the meta-conceptual role of Information and Communication Theory is historized and it becomes an integral part of a systemic method for the restitution of the electronic musical work. With a wide range of examples (including works by Edgard Varèse, Luigi Nono, Bruno Maderna, Gérard Grisey) we show peculiarities and issues of the critical editing of this repertoire.