What constitutes innovation in music production?

Innovation has often been at the core of record production, yet as production has advanced from Fred Gaisberg through the techniques of Musique Concrète to the plethora of possibilities afforded by the present digital age, the opportunities for genuine innovation might now seem limited. This notion is explored by considering the ontology of production with reference to audio examples, forming a chronological thread that highlights pieces commonly perceived as landmark innovations, their technological backdrops, and the recurrence/evolution of effect & aesthetic through successive generations of technology, and ultimately a nexus. The perception, attribution and value of 'quality' is another factor, and whilst this is a separate subject in its own right, some discussion of this better contextualizes the topic