Born in Buenos Aires, Argentina. He began studies at the age of eleven in Argentina with María and Hugo Ávalos, continued with Emilio Colombo, Manuel López Ramos and Abel López Iturbe, obtaining scholarship with Andrés Segovia, becoming a follower of his techniques.
He chose the ten string guitar because of the richness of tone which gives the possibility of playing pieces for the lute without the need for transcriptions.
From 1979 to 1995 he was profesor of music and guitar at the Conservatory Manuel de Falla in Buenos Aires. Also gave Master classes at the Manhattan Institute for the Guitar, Central Conn. State University and Marymunt Manhattan College in U.S.A.
He conducted the radio program El Mundo de la Guitarra (The word of the Guitar) in L:R:A: (Public Radio National) in Buenos Aires. He was a member of jury for international music competitions. Composed Preludios Americanos, Amanecer and Homenaje a Luis Gineste.
Küper recorded for the recording companies ION and ATC. In 1990 he inaugurated a series of compact discs for International Chamber Music Solist organised by RNE and RTVE (Spanish Radio ant Television) along with Plácido Domingo and Alfredo Kraus.
He performed throughout Argentina, in the most important theatres, such as the Teatro Colón, auditoriums and universities, as well as, in several radio and television programs. Also in Europe in theatres, auditoriums, universities and television of Spain, Belgium, Holland, Italy, England, France und Turkey.
On July 9th, 1998 he was invited to participate in the 17th international Festival of Istanbul along with celebrated musicians such as J. P. Rampal and Alicia de Larrocha, among others.
In Canada he played for The National Radio of Montreal and the University of Ottawa. In the United States at Carnegie Hall and the University of Columbia, Central Conn. State, Bridgeport, Yale and Hartford.
Küper filmed concerts for the RAI, Italian Radio and Television, Recorded for Vatican Radio and gave a concert for Pope John Paul II.
In 1993 he received the award Premio Divulgación Musical offered by The Casa de Cultura Americana in Buenos Aires, sponsored by the organisation of American States.
In Europe where he resides, he teaches guitar and plays concerts as solist and with orchestras.