SVG icon should be installed uncompressed
Not all DE's, for example GNOME, support compressed SVG icons for desktop entries, and the XDG icon theme specification does not mention svgz at all. http://standards.freedesktop.org/icon-theme-spec/icon-theme-spec-latest.html
I suggest installing the kid3 and kid3-qt SVG icons as uncompressed svg instead of svgz.
Imported from SourceForge, author: scop