Throw a bunch of New England Conservatory grads on a stage, and you can’t help but expect excellence. I knew going into the Lake Street Dive show this past Friday that I would see a tight, bluesy band fill up the State Theatre with sound. I was far from disappointed — Lake Street Dive brought even more presence and expertise than even I expected. The show opened with PWR BTTM, an energetic duo I’ve hoped to see for months. They emerged on stage, fully prepared to fill the mixed crowd of Ithaca natives and college students with their gritty, glittery garage-punk.