Marimba and organ - advanced to difficult - Digital Download SKU: S9.Q6225 Composed by Jean Guillou. This edition: Sheet music. Downloadable. Op. 67. Duration 12 minutes. Schott Music - Digital #Q6225. Published by Schott Music - Digital (S9.Q6225). The French composer Jean Guillou (born 1930) has composed a whole series of works for the organ plus a single instrument which are collectively entitled Colloques. This is all that needs to be said on the intention of the pieces: these are ‘dialogues’ between the organ and a solo instrument, conducted on an equal footing with each feeding the other lines. The most recent work is written for a relatively rare, yet all the more fascinating instrument: the marimbaphone. This is a demanding concerto work for virtuoso musicians.