Wagner’s vaunted model of artistic synthesis persists in scholarly assessments of his work. But at its centre, the composer argued that the media of voice and orchestra do not mix: they retain their identities as separate channels of sound that can neither duplicate nor substitute for one another. Taking as a starting point Wagner’s claims for the non-adaptability of media, this article addresses the adaptation of Wagner’s music to the modern digital technologies of HD cinema and video game. Drawing on a wide circle of writers, from Schiller and Žižek to Bakhtin, Augé, Baudrillard and second-generation media theorists, it interrogates the concept of ‘reality’ within live acoustic performance, both historically, as a discursive concept, and technologically, via the sensory realism of digital simulcasting and telepresence. The philosophical opposition of appearance and reality fails when reality is defined by the intimate simulation of a sensory event as it is registered on the body. And by contrasting the traditions of high fidelity in (classical) sound recording with that of rendering sound in cinema, I suggest ways in which unmixable media appear to have an afterlife in modern technologies. This raises questions – in a post-Benjamin, post-McLuhan context – about our definition of ‘liveness’, the concept of authenticity within mediatised and acoustic sounds, and our vulnerability to the technological effects of media.