Duo Gazzana Kõrvits/Schumann/Grieg ECM Records   Sisters Natascia Gazzana, violinist, and Raffaella Gazzana, pianist, have recorded a number of releases for ECM that program a combination of great romantic chamber works and contemporary fare. On their latest, they present romantic works by Robert Schumann and Edvard Grieg alongside contemporary pieces by Tõnu Kõrvits. The latter does a great deal to balance the former two, providing a less effusive tone and tangy harmonies.   Kõrvits’s Stalker Suite (2017) opens the recording. It was written for the Duo Gazzana and dedicated to the filmmaker Andrei Tarkovsky. The piece is titled after the