O n the face of it, Beethoven’s Violin Concerto, the opening work of this BBC National Orchestra of Wales concert, might have seemed unexceptional. Soloist Veronika Eberle immediately proved it otherwise. Sweet, pure tone, clarity of line and an almost reverential approach with not a trace of bombast distinguished her playing from the outset. The rapport with conductor Alexandre Bloch was implicit and, in the deeply reflective central Larghetto, the music was imbued with an air of serenity. Yet what made for a wholly different experience here was Eberle’s use of new cadenzas in all three movements, boldly commissioned from her fellow German, Jörg Widmann. Widmann realised a balance between the expected virtuosity and a highly imaginative, improvisatory feel, references to key Beethoven motifs tightly embedded.…