Franz Xaver Gerl have been the composer of the aria "Ein Weib ist das herrlichste Ding", for which Mozart wrote a set of variations for piano, K. 613 (the composer may instead have been another singer-composer in the troupe, Benedikt Schack). Mozart gradually came to participate more in the activities of the Schikaneder troupe, culminating in his opera "The Magic Flute" (1791), with libretto by Schikaneder. Gerl premiered the role of Sarastro, and continued to sing this part in many performances through 1792. He left Schikaneder's troupe in 1793. Gerl may have been a participant in a rehearsal of Mozart's "Requiem" on the
Piano concertos by Wolfgang Amadeus Mozart given by Cliff Eisen in 1997 is: Cadenzas to at least K. 466 and 467 also possibly existed. These cadenzas are part of the public domain and can be accessed here: http://imslp.org/wiki/36_Cadenzas,_K.624_%28Mozart,_Wolfgang_Amadeus%29 Piano concertos by Wolfgang Amadeus Mozart Wolfgang Amadeus Mozart wrote 23 original concertos for piano and orchestra. These works, many of which Mozart composed for himself to play in the Vienna concert series of 1784–86, held special importance for him. For a long time relatively neglected, they are recognised as among his greatest achievements. They were championed by Donald Francis Tovey in his "Essay on the Classical Concerto"