In January 2000 his second album Luna de Miel was issued, an interesting work where 10 female voices give some warmth to the compositions.
Curiously, the lyrics were written by Mastretta –with help from his brother, Fernando- and voiced by women from different nationalities: Julieta Venegas[4] and Alaska from Mexico, Rubi from Argentina, Beatrice from Italy, Gemma Corredera from Cuba, Rasha from Sudan and, from Spain Raquel Pascual, Irantzu Valencia from the band La Buena Vida, Cristina Lliso, Ana Belén and Ajo from the band Mil Dolores Pequeños.
Due to the concept of collaboration, only two live presentations were done in Madrid for two days in May 2000 at the Colegio Mayor San Juan Evangelista.
In 2001, besides playing throughout the American continent beside Julieta Venegas, he composed the soundtracks for the feature film El Sueño del Caimán by Beto Gómez and the short film Desaliñada by Gustavo Salmerón, and in November, Música de Automóvil, an instrumental album that reflects his characteristic sound, but always with an unprecedented point of strangeness added.
He has performed at international festivals such as Pop Komm in Germany, Arezzo Wave in Italy, Sónar in Barcelona and in Mexico and the United States.