Music and art are complex areas of knowledge organisation, and this paper considers the connections between the classifications in both domains. It starts with an analysis of music and art facets, utilising the Dewey Decimal Classification and relevant KO literature. Four important connections emerge from the comparison: the interplay between medium and materials; the interweaving of forms, genres, corporeality, and medium; the idea of format and its links to physicality; the connections between iconography, music subjects and function. These findings as well as the resulting model of combined music-art facets, further our knowledge of music and art KO, as well as interdisciplinary classification.