http://www.unsw.edu.au/sites/default/files/documents/EAP Points 2014 revised_0.pdf
This is UNSWs table for bonus points for performers and athletes.
As you can see there is a music section which details various options for performance.
So if your a member of a national youth choir your probably good, but if you just performed at the opera house with your school probably not. (I performed there three times in primary school alone, so it's probably not a big enough achievement unless you were a part of one of the groups listed in the schedule)
As a general rule, these sort of categories will apply to UTS and USYD as well, though they may have an extra category or two.