There's two key ways to fry something in this case...
Do not force NTSC SNES power supply into Australia/UK/etc outlet. NTSC SNES power supply normally expects 100~120v input!
Do not force PAL SNES power supply into NTSC SNES. PAL SNES power supply outputs AC rather than DC!
You'd need a correct outlet voltage converter to use the US power supply.
Apparently there's also custom third-party power supplies for using American SNES in the UK. If you can get one, I believe that would just take an Australia outlet adapter.
Potential info here:
http://www.robwebb1.plus.com/snes/snes_hard.htm