knob twiddler
n.— «When it comes to diversity in electronic music, one of the most important distinctions for the festival presenters is balancing the programs between artists affectionately known as “knob twiddlers,” who sit behind a laptop, manipulating sound with a mouse; and musicians who are active performers, either using technologies to process sound from an instrument as they play it, or triggering sound through gestures.» —“A music festival with a different beat” by Andrew Gilbert Contra Costa Times (Walnut Creek, California) Aug. 30, 2007. (source: Double-Tongued Dictionary)