From a young age, Karl was making recordings with his parents’ old reel-to-reel tape recorder, building instruments, and gradually acquiring synthesisers, samplers, and sequencers along the way. At 17, he left school to work as a trainee sound engineer, working extensively with tape and early digital technologies and then began composing theme music, soundtracks, and scores for films.

Having written for, co-produced, performed in, and toured extensively with multiplatinum-selling Supergroove in the 90s, his curiosity was constantly fuelled by second-hand bookstores visited on the road, and once back to sedentary life he moved to the UK where he completed a PhD in Ancient Greek and Roman Philosophy from Trinity College Cambridge.

His return to New Zealand would see him fully dedicated to his craft as a screen composer, earning him numerous accolades including an unprecedented 7 wins in the APRA Screen Music Awards across multiple projects in the ‘Best Original Music in a Film’ and ‘Best Original Music in a Series’ categories in the last few years.

His recent work includes Ant Timpson's Bookworm (Fantasia Festival/Fantastic Fest), starring Elijah Wood, Nell Fisher, and Michael Smiley, Uproar (TIFF) with Julian Dennison, Rhys Darby and Minnie Driver, directed by Hamish Bennett and Paul Middleditch, and Lucy Lawless’ directorial debut Never Look Away (Sundance/SXSW) scored with Jason Smith. His score for Ant Timpson's black comedy thriller Come To Daddy starring Elijah Wood was celebrated by reviewers from Variety, Rue Morgue, Film Music Magazine, and was among the Film Music Institute's Best Scores of 2020.

Other recent work includes Nathan Price's feature documentary for Universal The Subtle Art of Not Giving A #@%!, the documentary series Black Coast Vanishings with Rob Thorne, and the Black Hands series produced by Warner Bros, with series producer Robin Scholes.