Every new release in Andris Nelsons’ Boston Shostakovich cycle is an event. Following two universally praised installments, this one cleverly links Symphony No. 1, completed when the composer was 19, with Symphony No. 14 and Symphony No. 15 from nearly a half-century later. The theatricality and vivacity of No. 1 is wonderfully captured, just as the quirky No. 15—with its numerous allusions, including Rossini’s “William Tell: Overture” and Wagner’s Ring Cycle—is met head-on to great effect. The song-symphony No. 14, with its two fine soloists, is another superb achievement. It’s both atmospheric and, at times, unsettling. Russian conductor and violinist Rudolf Barshai’s expansion of String Quartet No. 8 gives the superb Boston strings a chance to shine.