I want to say a special word about Dave Malloy's "Preludes," because it is the work of an artist who is not afraid to try things, or to create worlds that haven't necessarily been seen before, and, trust me, this is more unusual than you think. Malloy's previous piece, the electro-pop opera "Natasha, Pierre & The Great Comet of 1812," was, after it opened in 2012, a relatively big hit for a musical based on Tolst…