Born in Trostberg,[1] Siegel studied at the Leopold Mozart Centre in Augsburg[2] with Kammersänger Liselotte Becker-Egner.
After engagements at the Theater Trier from 1993, the Anhalt Theatre [de] from 1995 and the Staatstheater Nürnberg from 1998 to 2006,[2] the singer worked freelance.
[1] He made his debut at the Royal Opera House in 2004 as Mime in Wagner's Der Ring des Nibelungen.
[1][2] He has worked with conductors such as Antonio Pappano, Jeffrey Tate, James Levine, Ivor Bolton, Zubin Mehta, Jesús López Cobos, Sylvain Cambreling and Christian Thielemann.
[3] In 2016, Siegel was Midas in Die Liebe der Danae by Richard Strauss at the Salzburg Festival, staged by Alvis Hermanis and conducted by Franz Welser-Möst.