As clubgoers stood in line outside the 9:30 Club on a chilly Monday night, a car slowed and eventually came to a stop. Down came the window and two girls yelled out, “Who’s playing tonight?” “The Deftones,” came a response. “What do they sound like?” “They’re heavy,” shot back a fan. That’s about as good as you can get in describing the Deftones without getting too far into mixed genre terminology — they’re heavy. The…