I was using Audacity 2.0.3 with Snow Leopard just fine and after installing Mavericks it started up and I tried adjusting I believe the output setting and then Audacity crashed and every time I try to open it (even after downloading and installing 2.0.5) it crashes. I figure there’s some pref somewhere that needs to be removed but I can’t locate it.
Purging the audacity.cfg file solved this issue. I don’t know if you provide a read me on new installs with suggests doing this or provide an installer which automatically performs this, but, it seems necessary to alleviate issues associated with the user performing OS updates.
If resetting something in Audacity’s audio I/O preferences solved the crash, I would think this means Mavericks is unstable (or a particular audio device you have cannot work with Mavericks).
It is not normally necessary to reset Audacity preferences when updating the Mac OS (I never heard of problems with updating from Lion to Mountain Lion, for example). But this may prove to be an issue with Mavericks.
If you give us the crash report and Help > Audio Device Info… from Audacity, we could see if we can figure out what happened. It’s just a guess without some information to go on.