Under Stock's direction, the Chicago Symphony became one of America's top orchestras, developing a distinctive brass sound already heard in its first recordings. An enthusiast of modern music, Stock championed the works of many then modern composers including Gustav Mahler; Richard Strauss (who, at Theodore Thomas's invitation, had been the CSO's first-ever guest conductor on subscription concerts in April 1904); Stravinsky, whose "Symphony in C" was commissioned for the orchestra's 50th anniversary; Sergei Prokofiev, who was soloist in the world premiere of his "Third Piano Concerto" in Chicago (although he recorded it in 1932 with the London Symphony); Gustav Holst; Zoltán Kodály, whose "Concerto for Orchestra" was commissioned by Stock; Nikolai Myaskovsky, whose Symphony No. 21 was commissioned for the orchestra's 50th anniversary; Josef Suk; William Walton; Arthur Benjamin; George Enescu; and many others. Stock and the Chicago Symphony debuted the Symphony in E minor by Florence Price on June 15, 1933, Price's first symphony and the first composition by an African-American woman to be played by a major orchestra. Stock's most memorable recordings were of Romantic repertory by Schubert, Schumann, Weber, Goldmark and Glazunov.