For OSX, there is nothing, nothing at all
Many years ago Macromedia released SoundEdit 16. It hasn't been updated for a very long time, but it still kinda works with OS9 (some functions don't work). To date nobody has released a decent OSX compatible multi-track audio recorder/editor.
I remember almost a decade ago when for very little $$$ you could use say a Quadra 840av to master a CD. Not anymore...nope. There are about a bazillion 2 channel sound recorder/editors, many with very decent interfaces that work with OSX, but they don't do much good without multi-track capability. There are some multi-track sound apps, but they really, really suck big time.
You could use FinalCut Pro, but that's extreme overkill and $$$$$.
Ah, the good ole days of SoundEdit 16. I don't know why Apple didn't buy this when they purchased Final Cut from Macromedia. They bundle Peak with FinalCut, but Peak lacks much of the functionality that SoundEdit had.
I wish someone would take SoundEdit 16 and carbonize it. Keep it elegant, simple, and clean...perhaps add the new sound formats and newer inputs. Then create a non-destructive editor (again, simple and clean) and integrate the two into one package...hell, call it iStudio!