Picture a roomful of New York record execs, and one might imagine some sleek Midtown office where cynical moguls strike big deals over cocktails and yellowtail tartare. Then there’s the crew at New Amsterdam Records, the prestigious local label known for releasing some of the nation’s most cutting-edge new classical and “post-genre” music. The setting for a recent listening session: their publicity director’s kitchen table. The spread: Popchips and coffee. Short on manpower, they did double-duty stuffing envelopes for a press mailing.