In short time, he attracted the attention of Kodály himself, who developed a lifelong teacher-student relationship with Joó, which lasted until the death of the composer.
During his studies in the Kodály school he was introduced by his teachers to visiting musicians such as Igor Stravinsky, Aram Khachaturian, Pablo Casals, Carl Orff, Yehudi Menuhin, and Dmitri Shostakovich.
At the age of 17 he was invited to give a solo recital in the Montreux festival (Switzerland) in the same series as Martha Argerich, Geza Anda and Arturo Benedetti Michelangeli.
At the age of 20, Joó emigrated to the United States, to study at the Juilliard School in New York City as a special student.
In his first year of study at Juilliard, he won first prize of the International Franz Liszt Piano Competition in Boston, Massachusetts.
During this time he also studied conducting with Igor Markevitch in Monte Carlo after which he was named the resident music director and principal conductor of the Knoxville Symphony Orchestra in Tennessee at the age of 24.
For the next 15 years, he conducted many of the leading orchestras of the world and toured in Germany, England, Italy, Austria, Hungary, and the Netherlands.
In 1987, Joó recorded the complete orchestral works of Franz Liszt for which he has received the coveted "Grand Prix du Disque" in Paris, directly from the French Minister of Culture, Mr.