Try BOOM.com, it is based in Hong Kong, it allows you to trade in multi markets oz and the us.
I live in England and I've been using them for 10 years since their startup trading onthe HKSE. No complaints at all ever, cheap and level 2 data reasonably priced, with rebates on number of trades. Their cutsomer service is very good.
I irate them highly.
Regards
Ascot trader