I came to Cole Porter's songs late in life, in part because I'd immersed myself in the lieder of Schubert, Schumann, and Brahms during my graduate-student days. Like most people, I'd heard some of Porter's signature tunes in elevator-music arrangements, and as a movie buff I'd enjoyed Marlene Dietrich's world-weary rendition of "The Laziest Gal in Town" in Stage Fright as well as Barbra Streisand's triumphantly gleeful "You're the Top" in What's Up, Doc?--but in general I still considered show tunes relatively unsophisticated. Then one day a friend played me Ella Fitzgerald's 1950s recordings of the Cole Porter songbook, and her performances turned me into a fan in a matter of hours, with an avid appreciation of Porter's wise, bittersweet lyrics, his clever rhymes, and the emotional suspense he could create between refrains--a talent almost equal to, say, Schubert's skill at contouring words to music. Next week at Petrillo, about 20 of Porter's tunes--including standards like "I Love Paris" and "Too Darn Hot" as well as less familiar numbers such as "Were Thine That Special Face," "We Open in Venice," and "Friendship"--will be presented by a quartet of classically grounded vocalists, each of whom has been through the mills of musical theater. Soprano Susan Egan was the original Belle in Disney's Beauty and the Beast, mezzo-soprano Debbie Gravitte won a Tony for her performance in Jerome Robbins' Broadway, tenor Rob Evan has sung Jean Valjean in Les Miserables, and bass William Michals is also a Beauty and the Beast veteran. Providing accompaniment will be the Grant Park Orchestra and Chorus; the orchestra, which shares many of its members with the Lyric Opera's ensemble, has a knack for brightening up show tunes, and Grant Park Chorus director Christopher Bell, who certainly doesn't need to brush up his Porter, will conduct both chorus and orchestra. Wednesday, July 31, 6:30 PM, and Friday, August 2, 7:30 PM, Petrillo Music Shell, Columbus at Jackson; 312-742-4763.