Danish String Quartet Keel Road ECM Records ECM 2785   Rune Tonsgaard Sørensen, Violin, Clog Fiddle, Harmonium, Spinet, Voice, Whistle; Frederik Øland, Violin, Voice, Whistle; Asbjørn Nørgaard, Viola, Voice, Whistle; Fredrik Schøyen Sjölin, Violoncello, Bass, Voice, Whistle; Nikolaj Busk, Piano; Ale Carr, Cittern   The Danish String Quartet have explored music from many eras and styles. Keel Road  (ECM, 2024), is the third recording in which they delve into Northern European folk music, ranging through Scandinavia, Britain, and Ireland; they call it “a musical journey through the North Sea.” The arrangements were made by the quartet, and in addition to