Adobe has released a Beta version of Audition for Mac via their Labs site (http://labs.adobe.com/technologies/audition/). If you haven’t downloaded it yet get to it now. It’s a very powerful sample and multitrack editor for audio.
While I’ve only played with it for a short time and consequently haven’t examined all features in depth these are my initial highlights:
As well as the waveform and Multitrack views, the Spectral view allows you to cut out/ paint out frequencies just like Izotope RX does. While the algorithms are not as powerful (yet) as Izotope the functionality being available in a free Beta version is a joy to behold.
Edit to Picture
Not quite as intuitive as I’d have hoped for but adding a video to a multitrack session allows you to ‘clean-up’ the associated audio as well as obviously laying new audio but to be honest Pro Tools is a better editor. The ability to spectrally edit to picture is (as far as I am aware) unique.
The application runs on Core Audio so anything that you can already use on your Mac will work happily with the application.
As mentioned above, current pricing is $0 (£0). The PC version which has now reached version 3 is listed at $349 and I’d imagine that after this beta period the Mac version would be equivalent.