For the penultimate volume in their Prism series, the Danish String Quartet juxtaposes Beethoven’s penultimate quartet, the String Quartet No. 15 in A Minor, Op. 132, with Mendelssohn’s String Quartet No. 2 in A Minor, Op. 13, written within months of Beethoven’s death and clearly a tribute to the great composer. The Danes’ approach to this music has a wonderful vitality, energy, flexibility, and, where necessary, poise. When combined with the glorious acoustics of the Reitstadel Neumarkt concert hall, this is a powerful and, at times, rightly unsettling experience. The little Bach “Fugue in G Minor” makes a perfect opener to the profundities of Beethoven’s searching, questing five-movement Quartet, whose language, in turn, inspires writing of intensity and deep songfulness in the young Mendelssohn.