Amadeus Lite for Mac

From HairerSoft:

Amadeus Lite is an intuitive and powerful wave editor supporting a variety of sound formats including AIFF, Wave, MP3, WMA, AAC, Ogg Vorbis, Apple Lossless, and many others.

Wave Editor
Amadeus Lite is a fully featured wave editor featuring smart editing, automatically preventing the appearance of cracks when performing editing operations. It also allows to paste a sound "over" an existing sound, performing a mix and has extensive built-in support for markers, facilitating the navigation in large documents.

Audio Units
Besides having many built-in sound effects, Amadeus Lite comes with full support for Apple's Audio Units. These are sound effects developed by third parties (a few of them are developed by Apple and are built into Mac OS X) that allow to extend Amadeus Lite's possibilities without limits.

File Conversion
Amadeus Lite converts audio files from and to no less than 13 sound formats, including AIFF, Wave, Mp3, Mp4, M4a, Ogg Vorbis, WMA, FLAC, and CAF.