This mutes the Character Creator music. AKA Menu Music.
The files muted are:
city of heroes/data/sound/ogg/N_UI/Music/N_MenuMusic_loop.ogg,
city of heroes/data/sound/ogg/frontend/v_menumusic_loop.ogg,
city of heroes/data/sound/ogg/frontend/h_menumusic_loop.ogg

Thanks to Red Oubliette for their help finding these, and everybody else for their help and encouragement. Even Snarky.