I think ABC Radio was called ABN for only about a year.
When ABC Radio became ABN, the idea was to have lots of live programs with music and vocalists, etc., especially during the daytime hours, to try to build on the success on Don McNeill's "Breakfast Club".
Recorded music and simulcasts of ABC-TV network programs were banned.
But instead, ABC lost money on ABN (I believe the TV network was barely profitable at the time, so ABN losses may have plunged the whole company into a loss), and the network pulled the plug on all those live entertainment shows in 1958 and brought back the ABC Radio name.