Performers face unconventional situations when preparing real-time mixed music works. Specifically, the technological context (computer and audio setups) as well as the social context (computer sound designers, musical assistants or sound engineers) extends the performance environment. In this chapter, we investigate instrumentalists’ expertise as it relates to acts of apperception, appropriation, and interaction with live electronics in case of solo works. We conducted semi structured interviews with twelve instrumentalists and analysed the data according to grounded theory. This study revealed, notably, a broad range of work strategies, departing from those in instrumental music, that performers implement in their appropriation of this repertoire. Both the technological and the human requirements, specific to this repertoire, critically transform the production context. We argue that solo works with live electronics are developing a new paradigm for chamber music and participates in a critical transformation of chamber music's definition.