The way we perceive music, interact with musical instruments and produce music has changed. Based on new digital technologies and electronic and scientific concepts, musical instruments today differ fundamentally from traditional acoustic instruments. Thanks to micro controllers and a wide variety of sensors, there are no limits to the imagination when it comes to the design of new music instruments and interfaces for musical expression. However, this also raises new questions that go beyond the technical and sound-related evolution of interfaces for musical expression. How do we interact with these new instruments? How are they operated? Are approaches such as the traditional keyboard still a point of reference, or can the numerous possible interactions based on sensor technology and computer programming be formalised within a more contemporary classification? This article proposes a concept for analysing new musical interfaces and their interaction in a new light. It includes the description of the site-specific interactive sound installation Netz 2.0, which introduces a spider web-like instrument topology offering an interaction method based on stretching and pulling elastic strings.