Tango was made by immigrant communities in the bars and bordellos of 19th-century Buenos Aires, a tangle of glowering love songs and bygone classicism. Astor Piazzolla, who wrote more than 300 of them, was born in Argentina to Italian parents, grew up in New York and finessed his craft in Paris. None of this is pure-bred stuff, and Piazzolla’s music needs to be dirty and tragic as well as elegant. Dutch violinist Isabelle van Keulen goes full-throttle in her second Piazzolla album, with sultry virtuosity and massive vibrato that makes it easy to hear why she keeps coming back to this music. Her ensemble stays just the right side of glossy, but compared to Piazzolla’s playing of the big hits featured here – Otoño Porteño, Primavera Porteña or Le Grand Tango – the Keulen Ensemble lacks a certain private grief. The exception is Soledad, which is spacious and deeply sad.