Now in its sixth year, the marathon music experiment Drone Not Drones returns to raise money for the humanitarian organization Doctors Without Borders. This year, the 28-hour stretch of uninterrupted drone music brings back alumni like Low’s Alan Sparhawk (whose band is just a few months removed from Double Negative, their best-received album since the early 2000s) and Duluth folkie Gaelynn Lea, among dozens of others. And yes, you’re welcome to bring a pillow. Show starts at 7 p.m. Fri., Feb. 25 and ends at 11 p.m. Sat., Feb. 26.