Fernando Sor's opus nine consists of variations for guitar of a theme by this composer. Another theme by this composer provided the basis for the variations and fugue by Max Reger. He wrote his clarinet concerto in A major for Anton Stadler, and composed a fugue based on five themes in the fourth movement of his last symphony. Tchaikovsky's fourth 
Fernando Sor's opus nine consists of variations for guitar of a theme by this composer. Another theme by this composer provided the basis for the variations and fugue by Max Reger. He wrote his clarinet concerto in A major for Anton Stadler, and composed a fugue based on five themes in the fourth movement of his last symphony. Tchaikovsky's fourth orchestral suite is based on works of this composer, including his setting of the Ave verum corpus. According to legend, he transcribed Giorgio Allegri's Miserere from memory at age twelve, and his works are categorized by Köchel numbers. For 10 points, name this composer of the Jupiter symphony and Eine Kleine Nachtmusik.
Fernando Sor's opus nine consists of variations for guitar of a theme by this composer.
Wolfgang Amadeus {Mozart}