It's a case of love at first hearing for most people on being introduced to the music of Astor Piazzolla, the Argentinian composer whose tango opera Maria de Buenos Aires will be performed at the Hong Kong Arts Festival. Over the past year or so, symptoms of something that could develop into full-blown tango fever have been manifesting themselves among local music lovers. At last year's arts festival, classical music audiences thrilled to the novelty of tango sounds in a concert of contemporary music given by celebrated violinist Gidon Kremer, an ardent Piazzolla champion, and his group Kremerata Baltica. Six months ago, the City Chamber Orchestra of Hong Kong presented an all-Piazzolla concert that was warmly received by an audience eager for something new and exciting. And now there is Maria de Buenos Aires, waiting in the wings. She is a bird of paradise, a creature of smouldering and erupting passions, a flamboyant symbol of a city and a culture. A painted lady whose home is the world of nightclubs, cabarets and brothels. And she sings the most heart-achingly beautiful music heard in a long, long time. And she is not even a proper opera. Something in-between, a hybrid some call 'music theatre' for want of a better description. And she dances the tango. The other thing about her is she isn't all that young. The opera that seems to be 'hot news' to many serious classical music fans is, in fact, 32 years old. Piazzolla's music - an irresistible blend of traditional tango, jazz and classical music - is enjoying a vogue in concert halls around the world, and has been seducing audiences in Japan for quite a while. So it was no big surprise to see Maria turn up as the opera offering of the festival. 'There was unanimous agreement with the organising com mittee that this was the opera for the season, given Piazzolla's growing popularity,' said Lau Chun-keung, the arts festival associate programme director. The musicians involved include the acclaimed Flemish chamber music group I Fiamminghi, with Argentinian singer Laura Lahera in the title role. Maria de Buenos Aires is hard to describe, and is therefore best left to be experienced. Maria herself represents the tango and its evolution, as well as modern Buenos Aires. The setting is a cafe, and the cast of characters is the cream of low life - prostitutes, pimps, gangsters and drunks. The lyrics, by Uruguayan poet Horacio Ferrer, are surreal: out of context sounding baffling to the point of being nonsensical, but hauntingly eloquent sung in Spanish and set to Piazzolla. City Chamber director Leann Nicholls said it was an 'extraordinary' experience performing Piazzolla. 'The music is refreshingly new and innovative. It is passionate, soulful, and infectious. You feel excited, yet relaxed playing it. The thing is the more you hear this music, the more you want to hear.' Music critic and director of the Bach Choir, Jerome Hoberman, said Piazzolla's music is uniquely enjoyable in that performers can relax and yet have a sophisticated music-making experience. 'And the excitement the musicians feel is communicated to the audience. So everybody has a great time. This is tremendous music. There is no question that Piazzolla is one of the real geniuses of 20th century music.'