Think of it as a sort of classical supergroup: the Moscow Virtuosi Chamber Orchestra and its violin-slaying maestro, Vladimir Spivakov, is made up of the top-ranking soloists from all the great symphonies of Russia. That helps explain the praise heaped on the ensemble, whether it’s been the Washington Post raving about “a sound that would put many full orchestras to shame” or the New York Times commenting on “first-class string performers brought to perfection by Maestro Spivakov.” The chamber gods make a rare appearance here on their 35th anniversary tour, with works by Mozart, Tchaikovsky, Shostakovich, and Piazzolla, at the Chan Centre for Performing Arts on Tuesday (May 6).