This chapter discusses the agencies of composer, performer and sound engineer respectively, and further of non-human agents such as score, instruments (widely defined), the concept of authenticity in the making of the premiere recording of William Brooks composition entitled Footnotes, composed  between 1983 and 1985, but never performed in its entirety before this recording by Stefan Östersjö. With the collaboration of Jez Wells, sound engineer, and William Brooks, a 45-minute LP was produced which aim to reconstruct the historical sound of certain musicians and recording technologies. The entire working process was documented on video and analysed using qualitative research methods. Early in their work it became evident to the three collaborators that the overall project required the construction of a set of different identities for six types of participant: guitar, guitarist; score, composer; hardware, engineer. This chapter—itself an intertangled multilogue of mutable voices—traces the construction of, distinction between, and eventual representation of, those identities in the final recordings, but most of all, through an analysis of the extended collaborative process.