He was a child prodigy and entered the service of Duke Ferdinand Maria Innocenz of Bavaria at the age of 12 as an oboist. The newly constructed Bavarian Court Theatre (the Old Residenztheater, now known as the Cuvilliés Theatre after the architect) in Munich opened on 12 October 1753 with Ferrandini's opera Catone in Utica. A recording of the opera made 250 years later in the same theatre is available (Oehms Classics OC 901).
^Bruce Haynes The eloquent oboe: a history of the hautboy 1640-1760 2001 Page 339 "Among the composers were Torri and Giovanni Battista Ferrandini. Ferrandini, a ' Wunderknabe', had first entered the service of Duke Ferdinand in Bavaria at the age of 12 in 1722. At that time he was an hautboy player." - this must be
^Darwin Floyd Scott For the love of music: festschrift in honor of Theodore Front 2002 Page 52 "... Giovanni Battista Ferrandini (ca. 1710-1791) was active in Munich, where his opera seria Catone in Utica opened the new Cuvillies Theater at the Residenz in 1753.