You can use any encoder for broadcasting live from your Mac as long as it is compatible with the Icecast2 server type. Not sure where to start? Here are several options that are free or low cost:
Mixxx - Free and open-source, Mixxx is excellent for LiveDJs. The interface is very configurable and can be setup to run in several languages.
Nicecast - Free Demo for up to 60 minutes, and then Nicecast will insert a sound block. It is $40 as a one-time payment for the license.
Virtual DJ - Virtual DJ has a "free" home use version. To unlock the streaming portion you will need to have a license. With Virtual DJ you can do a one time payment ($299) Or a monthly subscription (19$/month).
LadioCast - This is an Icecast compatible encoder that is free.
Broadcast Using This Tool Free Icecast compatible encoder for Macintosh. Great for live voice broadcasting.
Megaseg - Not free but a low cost (comparatively speaking) Automation and live mixing application for Macs 99$/one time purchase.
Please note that which ever applications you choose, when streaming music the application will need the ability to send Live365 the metadata of the track (song title and artist) to keep your broadcast in compliance with the DMCA rules.