TwistedWave is a very easy to use and powerful audio editor. It supports Audio Unit plug-ins and many file formats, including wav, aiff, caf, mp3, mp4, FLAC, Ogg/Vorbis. Good multichannel support: you can apply Audio Units to a selection of channels. Unlimited undo and redo which works instantly. Zooming in and moving around the waveform is very fast, even with very large files. All the effects are applied in the background, saving a lot of time.