Waldo De Los Rios has been played on NTS shows including Geologist Presents: The O'Brien System, with De Dónde Vienen Las Guitarras first played on 6 January 2017.

Waldo de los Ríos (7 September 1934 - 28 March 1977) was an Argentinian composer, conductor and arranger.

He is best-remembered for his ability to transform European classical music into pop music. His 1971 arrangement of Mozart's Symphony No. 40 recorded with the Manuel de Falla orchestra, reached the top spot in the Dutch charts and scored a top 10 hit in several other European countries. In 1970, prior to this success, Waldo de los Rios had already climbed the charts around Europe and America with Ludwig van Beethoven's Ode To Joy which he arranged and conducted for Miguel Rios.

His record Mozart in the Seventies rearranged famous Mozart pieces in a contemporary style, with a large percussion section. Several tracks from it were used as theme tunes to BBC programmes of that era, including the theme to the BBC's coverage of the Horse of the Year show.

He also issued an album "Symphonies for the Seventies" which included Mozart's Symphony no. 40 and other major composers including Dvořák's New World. In 1971, he arranged and conducted the Spanish entry for the Eurovision Song Contest, "En un mundo nuevo" for Karina. The song landed a respectable second position and hit the charts in several European countries.

A victim of an acute depression while working on "Don Juan Tenorio", De Los Rios committed suicide in Madrid in 1977