In metal music studies, “heaviness” has been acknowledged an essential element of the genre. Commonly associated with the distorted guitar, most work on heaviness has concentrated on the instrument’s sound. If respective research considered structural aspects of the guitar riff, then with a special focus on tempo, rhythm, tonality and form. This article analyses the interaction between distortion and harmonic structures on the electric guitar. Operationalising heaviness with a psychoacoustic model of sensory consonance, an acoustic experiment explores how guitar distortion affects acoustic features of harmonic structures. Since acoustic studies are limited in predicting perception, a listening test investigates distortion’s influence on listener perception. The findings indicate that both increasing distortion level and harmonic complexity reduce sensory consonance, especially when acting together. Acoustically, distortion shows a slightly stronger effect strength than structure; perceptually, the ratio is dependent on person-specific characteristics. Metalheads seem to be only little affected by sensory dissonance.