Jon Terryl "Terry" Plumeri (November 28, 1944 – March 31, 2016) was an American musician, classical composer, orchestra conductor, double bassist, lecturer, teacher, producer, and film score composer.
Ezio Bosso (13 September 1971) is an Italian composer, classical musician and conductor.
 Born in Turin, Italy, Bosso learned to read and play music before the age of four.
 At the age of 14, he became the bass player for the band Statuto.
 Bosso later abandoned popular music, in order to become an orchestral conductor and classical composer.
 He conducted such prominent orchestras as the London Symphony Orchestra.
Antonio Braga (22 January 1929 – 26 May 2009 in Naples) was an Italian classical composer.
 Born in Naples, he wrote ballets, concerto, ouvertures, symphonies and three operas.
A Little Nightmare Music is an opera in "one irrevocable act" by Peter Schickele under the pseudonym he uses for parodies and comical works P. D. Q. Bach.
 The title of the work refers to the English translation of Mozart's famous "Eine kleine Nachtmusik" ("A Little Night Music").
 The opera is described as being "based on a dream he had December 4, 1791, the night that Wolfgang Amadeus Mozart died and Antonio Salieri didn't."
 The opera was "newly exhumed" (a.k.a. premiered) at Carnegie Hall on December 27, 1982.
 It was later recorded with the premiere cast and released on CD by Vanguard Records in 1983.
 The album also includes two other works by P. D. Q. Bach: an octet (Octoot for wind instruments) and a parody of Handel's "Water Music" and "Music for the Royal Fireworks", Royal Firewater Musick.
Antonio Salieri (] ; 18 August 17507 May 1825) was an Italian classical composer, conductor, and teacher.
 He was born in Legnago, south of Verona, in the Republic of Venice, and spent his adult life and career as a subject of the Habsburg Monarchy.
Giuseppe Silvestri (1841-1921) was an Italian classical composer and mandolin virtuoso.
 He is principally remembered today for his role as a mandolinist and for his composition "Serenade d'Autrefois" ("Serenata medioevale" or "Serenade of Olden Times").
 He was a celebrated teacher of the mandolin in Naples and Paris, and became popular enough to get the criticism that he was causing Parisians to leave the piano for the mandolin.
David Amram (born November 17, 1930) is an American composer, conductor, multi-instrumentalist, and author.
 As a classical composer and performer, his integration of jazz (including being one of the first noted as an improvising jazz French hornist), folkloric and world music has led him to work with the likes of Dizzy Gillespie, Lionel Hampton, Willie Nelson, Langston Hughes, Charles Mingus, Pepper Adams, Levon Helm, Betty Carter and Jack Kerouac.
 In the early 1950s, he was encouraged to pursue his unique path by mentors Charlie Parker, Thelonious Monk, the New York Philharmonic's conductor Dimitri Mitropoulos, Miles Davis, Aaron Copland, Gunther Schuller, and visual artists Jackson Pollock, Joan Mitchell, Willem de Kooning and Franz Kline.
 Today, as he has for over 50 years, Amram continues to compose music while traveling the world as a conductor, soloist, bandleader, visiting scholar, and narrator in five languages.
Carlo Pedini (born 19 June 1956 in Perugia) is an Italian classical composer.
Giovanni Andrea Fioroni (also Fiorini, Florono) was an Italian classical composer, maestro di capella and organist born in Pavia in 1716, although he had studied music for fifteen years with Leonardo Leo in Naples.
 He composed many operas, oratorios and about 300 sacred vocal works in a contrapuntal style, many of them for large choirs.
Adrien Barthe (born Grat-Norbert Barthe, June 7, 1828 – August 13, 1898) was a French classical composer.
 Born in Bayonne, Barthe studied music under Fernand Le Borne at the Paris Conservatory.
 An early composition, "Francesca de Rimini", was lauded by the Rome Institute, and subsequent cantatas "Judith" and "Don Carlos" were well received.
 Performances of "Aubade" in 1893 by conductor Paul Taffanel were popular with audiences to the extent that Taffanel published praise of Barthe - "your delightful work earned us our first success."
 Moving from classical composition to theatre work, Barthe's "la Fiancée d'Abydos" appeared on stage in Paris and Rome starring Jean-Vital Jammes, however flaws in the composition persuaded Barthe to retire shortly after December 1865, becoming a teacher.
 He died in Asnières, leaving behind several unpublished manuscripts.

Question: Under which government did this Italian classical composer, conductor, and teacher that became a source of inspiration for "A Little Nightmare Music" pursue his career?
Answer: the Habsburg Monarchy