When you listen to the choruses of Handel's Messiah, it's difficult to imagine that several of them have their roots in tiny Italian chamber duets. This latest in La Risonanza's glorious Handel series brings together 10 of his less well-known duets for soprano and mezzo: apart from O death, where is thy sting?, there is little that is recognisable, but they are a flood of endless invention. They use musical formulas, true, but what formulas! Endless roulades and bouncing sequences, aching suspensions and plangent harmonies, all delivered with La Risonanza's trademark combination of hard-edged tonal purity and expressive nuance.