In 1986, Jo 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.