All the brass horns gleam, whisper and shout. Tonal colors multiply, merge and melt, without digital trickery. Today's jazz orchestra composer-arranger's pen conjurs sumptuous landscapes for the soloist's ramble. Impressive recordings of them proliferate lately, some winning best-of-the-year polls and wide acclaim. But aren't big bands a creaking dinosaur of the swing era? Something is afoot, a reborn beast with a huge sonic footprint.