This paper reports on a project to produce a reconstruction of a pioneering work of live electronics, Mesa (1966) by the U.S. composer Gordon Mumma (b. 1935). A digital recreation of the work was presented at the Montreal/New Music Festival on 27 February 2017 by the author of this article and his collaborators: Jonathan Goldman (bandoneon), Francis Lecavalier (programming) and Ofer Pelz (electronic performance). This migration entailed a digital recreation of the fundamentally analog processes of the original work, undertaken with the composer’s explicit consent. Emerging from Cagean aesthetics, Mesa has a curious ontological status, since it is a product of a fairly radical indetermination. As such, Mesa and its digital reconstruction require an ontological and epistemological reconsideration of the musical work.