In 1984 Peres became director of ARIMM, the Atelier pour la Recherche sur l’Interprétation des Musiques Médiévales (or "Workshop for Research on the Performance of Medieval Music") with the support of the Fondation Royaumont, created by the Goüin family.
In 1994 the Atelier became CERIMM, the Centre Européen pour la Recherche sur l'Interprétation des Musiques Médiévales (or "European Centre for Research on the Performance of Medieval Music").
In 2001 Pérès and his group Ensemble Organum moved to Moissac where he founded CIRMA, the Centre itinérant de recherche sur les musiques anciennes (or "Itinerant Centre for Research into Ancient Music").
In 1982 Peres founded Ensemble Organum, a group specialising in "pre- and para-Gregorian" chant.
The group has been based at three medieval monastic sites.