What small labels do best is backing the owner’s hunches. BIS in Stockholm produced symphonies by Alfred Schnittke when he was unheard outside Russia. Hyperion in south London resurrected 19th century piano concertos. Cedille in Chicago backs off-beat US composers. Manfred Eicher’s ECM in Munich is the engine behind Arvo Pärt, Giya Kancheli and Chick Corea. These labels are often thelion kings of classical recording. We owe the rediscovery of Mieczyslaw Weinberg, a Polish refugee in Soviet Russia, to a father-son team in Colchester, England, operating from a mobile recording unit. Their company, Chandos, released its first Weinberg recording around…