Baroque Venice was a city of doubles – of shimmering reflections and masked revellers. And since nothing succeeds like excess, when Vivaldi wrote concertos for two soloists, the results were spectacular: a carnival of colour, illusion and sparkling sonic conversation. La Serenissima takes its name (and its no-holds-barred flamboyance) from Venice, and today, under the direction of its charismatic founder Adrian Chandler, it twists the musical kaleidoscope with double concertos for cellos, oboes, flutes and violins, plus a colourful ensemble concerto inspired by the shape-shifting river-god Proteus. Hearing is believing…