I suppose it's a ghost sign now, although McCann Brothers music is still running after all these years. It was founded in 1881, making it one of the longest continuous music stores in Australia. insidemusic.com.au/job/mccanns-music-centre/
This old sign clearly dates from early in the 20th century, as radios ("the wireless") first appeared commercially in Australia in 1913, when Australia Marconi and its main competitor, Telefunken, amalgamated to form Amalgamated Wireless (Australasia) Ltd. (AWA). The Macquarie Street building itself dates from the 19th century.