On the occasion of the 250th anniversary celebrations of Ludwig van Beethoven in 2020, we developed the musical room installation “Inside Beethoven! The Audience Goes on Stage”. It is a stage with virtual musicians. Visitors are invited to enter, take the position of the musicians and listen to each of them at close range. The installation emulates the listening perspective of the musicians, thus, providing an uncommon experience to visitors who are mostly used to listen to music from recordings or from a concert audience’s perspective. The musicians play Beethoven’s septet op. 20 and its trio arrangement op. 38, two exclusive 14 channel music productions. Both versions are aligned and can be switched seamlessly. Digital music stands visualize the score. In this paper we trace the genesis and construction of the installation and detail the conceptual and technical challenges tackled.