[xrr rating=2.75/5]The label “electronic soul,” one that Londoners Luca Santucci and Ben Fitzgerald have applied to their duo project Stubborn Heart, makes perfect sense as a descriptor for their music. From start to finish, the pair’s debut self-titled record, released in the UK late last year and in the U.S. last month, is full of authentic passion. Vocalist Santucci sings …