Multi-instrumentalist Kjartan Sveinsson has pulled out of Sigur Ros' world tour, but has not quit the band. He will be replaced on the group's upcoming tour by Ólafur Björn Ólafsson on keyboard and oboe, and Kjartan Dagur Hólm - younger brother of bassist Georg Hólm and member of For A Minor Reflection - on guitar. Sigur Ros will release Valtari on May 28.