There is a place where the sacred shades into the sensual. The point where chant clings to the silence of the nave, and the stone glows back in return. This is the tender line on which Nick Martin sets his Bittersweet, for the Icelandic KIMI ensemble. The trio of soprano, accordion and marimba points outwardly towards the street and the concert hall, but its insistent, chanting repetitions have the consistency of prayer.