Provided you are covered by APRA and PPCA licences for DJing at a “public” event, it is unlikely that you will need any special permissions to do a live mix or mash-up.

In some cases you might need to consider moral rights issues. For example, in some cases it may be feasible to announce the songwriters of the material you are using. However, it is difficult to comment on whether a mix might infringe a composer’s “right of integrity”. To succeed in such an action, a composer would need to show that his or her reputation or honour as a composer has been damaged or prejudiced as a result of the mix. This may in many cases be difficult to do.