I'm using iMovie and iDVD to edit and present video and that seems by
and large to suffice for my humble needs, but with one exception.

I'd like to be able to export the audio to e.g. SoundStudio and make
some changes to levels here and there and attempt to silence some
extraneous noises (the tools for fiddling with the audio in iMovie seem
a bit primitive). If I don't alter the overall length I then want to
re-import the audio to replace the original.

Any suggestions for OS X apps which can do this - or even have better
tools built-in?

Thanks -- tim