The Ensamble Nacional del Sur (ENS) is an electro-acoustic ensemble located in Buenos Aires, which specialises in contemporary classical music.

Now in its third generation of musicians, the group has performed many times in a number of Edelstein's acoustic theatre works, including El Caballo Fantasma (2012), the first part of the trilogy La Teoría Sagrada del Espacio Acoustico – Libro I (2000–2001) which according to Edelstein is about "the conflict between religion and technology, or if you wish, between creation and technology",[1] Klange, Klange, Urutau (1997) and El Hecho (1994).

The resulting spatial structures are the product of the development of timbrical, rhythms and/or dynamic curves produced by the performers, placed in fixed positions.

Martín Liut (La Nación) said, "With the ENS, Edelstein has found an "instrument" capable of making electro acoustic music, but with the traction of blood.

The complex polyrhythmic textures and tímbres are the launch platform for the exploration of the space in three dimensions, an obsession that, now, Edelstein can record in a top format (5:1).”[8]