Concert Hall / Hong Kong Cultural Centre / Apr 22, 2017 / Ernest Wan / Mahler’s Symphony No 6 constituted the bulk of this concert by the Hong Kong Philharmonic Orchestra with music director Jaap van Zweden – but the premiere of Conrad Tao’s swallow harbor that preceded it was just as interesting: a work inspired by Hong Kong is a rarity on the programmes of the city’s flagship ensemble. Born in Illinois to Chinese parents, the 22-year-old composer visits Hong Kong infrequently and, as he has said himself, his “portrait” of the city is based on his impressions during a short sojourn at the end of last year. Another influence, according to Tao, is Varèse’s early works, especially Amériques. In swallow harbor, there is no confluence, as one might expect, of western and eastern aesthetics à la Chou Wen-chung, a protégé of Varèse who is the grand dean of Chinese-American composers. Yet, sure enough, it employs a wide array of percussion instruments, begins with a sound incorporating a lion’s roar, from a friction drum, and abounds in fragmentary bursts of timbres and other explosive …