In 1996 Milen founded the Eva Quartet with Gergana Dimitrova, Sofia Kovacheva, Evelina Spasova, Daniela Stoichkova, all of them singers of "Le Mystère Des Voix Bulgares /The Mystery of Bulgarian Voices".

Under Milen Ivanov's conducting Eva Quartet has released a few independent albums and given concerts in some of the most prestigious halls all over the world.

The two of them created the vocal formation "Dvuglas" ("Two voices") and have given concerts in Bulgaria and abroad (Austria, Germany, Czech Republic, Israel, Denmark, Sweden, Switzerland, Corsica) and released independent albums containing Bulgarian folklore and church songs: “Historical and Renaissance songs”, “Bulgarian Diaphonic Singing”, “Thou Art Blessed,Lord”, “Christmas Blessing”.

In 2011 Daniel Spassov and Milen Ivanov along with „The Mystery of Bulgarian Voices" made records in BBC Radio, London.

In July, the same year, Svetoglas receive a special invitation to take part in the festival "Music of faith" in Kazan; and in September 2013, they took part in the „Thracian Gold from Bulgaria – the Legend Comes to Life" exhibition's opening ceremony in the State Historical Museum in Moscow.