made her European operatic debut as Gilda in Verdi's Rigoletto at the Teatro Comunale Giuseppe Verdi in Trieste. This performance drew the attention of Herbert von Karajan, who proceeded to cast her as Oscar in Un ballo in maschera opposite Plácido Domingo for the 1989 Salzburg Festival. Karajan's death during festival rehearsals prevented Jo from actually singing on stage under his baton (Georg Solti conducted the performances) but she did sing under Karajan in the studio recording of Ballo, made in the early months of 1989 for Deutsche Grammophon. In 1988, Jo made her La Scala debut as Thetis in Jommelli's Fetonte. That same year she made her debut with the Bavarian State Opera and sang Barbarina in The Marriage of Figaro at the Salzburg Festival. In 1989, Jo made her debut with the Vienna State Opera and returned to the Salzburg Festival to sing Oscar in Verdi's Un ballo in maschera. That same year, she made her debut with the Metropolitan Opera, once again portraying Gilda in Rigoletto. Jo would later reprise this role numerous times with the Met over the next fifteen years. In 1990, Jo made her debut with the Chicago Lyric Opera as the Queen of the Night in Mozart's The Magic Flute. The following year, she returned to the Metropolitan Opera for another performance as Oscar in Un ballo in maschera and made her Royal Opera, Covent Garden, debut as Olympia in The Tales of Hoffmann. She returned to Covent Garden the next year to sing Adina in L'elisir d'amore and Elvira in I puritani. In 1993, Jo appeared in the title role of Donizetti's Lucia di Lammermoor with the Metropolitan Opera and sang the role of the Queen of the Night at the Salzburg Festival and Covent Garden. The following year she made her debut with Los Angeles Opera as Sophie in Strauss' Der Rosenkavalier. In 1995 she sang the role of Countess Adèle in Le comte Ory at the Aix-en-Provence Festival. Over the next decade Jo maintained a busy schedule, singing Lucia in Strasbourg, Barcelona, Berlin, and Paris; La sonnambula in Brussels and Santiago, Chile; I Capuleti e i Montecchi with Minnesota Opera; Olympia and Rosina in New York; the Queen of the Night in Los Angeles; Gilda in Bilbao, Oviedo, Bologna, Trieste, and Detroit among others; Il turco in Italia in Spain; L'enfant et les sortilèges in Boston and Pittsburgh; Le comte