Opera house as they sing. This occurs in the Met's productions of operas such as "Aida" and "Tales of Hoffman". London's Royal Opera House, which was remodeled in the late 1990s, retained the original 1858 auditorium at its core, but added completely new backstage and wing spaces as well as an additional performance space and public areas. Much the same happened in the remodeling of Milan's La Scala opera house between 2002 and 2004. Although stage, lighting and other production aspects of opera houses often make use of the latest technology, traditional opera houses have not used sound reinforcement systems with microphones
La Scala citing "hostility" from staff members. In May 2005, Stéphane Lissner, formerly head of the Aix-en-Provence Festival, was appointed General Manager and Artistic Director of La Scala, becoming the first non-Italian in its history to hold the office. On 15 May 2006, Daniel Barenboim was named "Maestro Scaligero", or "de facto" principal guest conductor, of the company. In October 2011, Barenboim was appointed the next music director of La Scala, effective December 2011, with an initial contract of 5 years. In December 2013, management named Riccardo Chailly the next music director of La Scala, effective 1 January 2015. Stéphane Lissner left