 Despite its success abroad, the music of the quartet was not in favour in Bulgaria, where on occasion it had been banned as “politically inappropriate.” In 1968 the quartet recorded an album beyond the Iron Curtain in FRG, free of the aesthetic restraints of communism.In the same year he contacted the American bandleader Don Ellis, sending him recordings of Bulgarian folk music, including Sadovsko horo, a folk dance tune in 33/16, which Ellis rearranged and released under the title “Bulgarian Bulge.” This resulted in a yearlong collaboration between Leviev and Ellis, during which Leviev moved to the US to compose, arrange, and play piano for Ellis’ band.One of the most significant Bulgarian jazz singers is Lea Ivanova.