Master classes with Dietrich Fischer-Dieskau, Hans Hotter, Elisabeth Schwarzkopf (who supervised him for 24 years) and Eric Tappy made a significant contribution to his artistic development - as evidenced by numerous prizes and awards at international singing competitions.
Especially in the concert field Hauptmann made a name for himself under conductors like Bernius, Bernstein, Bertini, Boulez, Corboz, Gardiner, Rilling, Harnoncourt, Hogwood, Masur, V. Neumann, Tilson Thomas, Welser-Möst, Sigiswald Kuijken, Cao and others.
From December 2009 on, SWR and other affiliated radio stations broadcast a new lullaby every week for one year, 2 CDs and accompanying books were released.
This charity project ("Herzenssache" Foundation) is supported by the German Chancellor Angela Merkel as patron and by the publishers Reclam and Die Zeit.
[4] For this project Hauptmann was awarded the "Gräfin-Sonja-Gedächtnispreis"[5] by Count Christian Bernadotte[6] on the island of Mainau by the "Singen mit Kindern" Foundation in December 2011.