German conductor David Afkham makes his San Francisco Symphony debut with two timeless treasures of the Russian repertoire. Tchaikovsky’s only Violin Concerto wasn’t an immediate hit, but the composer was vindicated in time. Played here by Sergey Khachatryan, the concerto sells itself: a showpiece with a heart. Its hyper-hummable themes have escaped the confines of the concert hall and embedded themselves in the wider culture. Urgent and revelatory, Shostakovich’s Symphony No. 8 is the ideal soundtrack for an anxious age. Battling ill health, he composed it in just two months while on a state-sponsored sabbatical, far from the noise and chaos of wartime. Soviet authorities found it confusing and counter-revolutionary; today the Eighth resonates more powerfully than ever.