If you export an audition multitrack mixdown as a wave uncompressed file multiple times, do you begin to lose quality?
For example, if I export a project as a wave uncompressed file and pass it on to a friend, and he edits the project in audacity and then he exports it and passes it back to me, and then I make a few edits and export it yet again, do these multiple exports degrade the audio quality of the final product in any way?
They shouldn't - but I can't speak for Audacity, really. It's only compressed files that have to be decoded and then recoded that have the degrading issue. If your friend is only performing edits on the mix, that shouldn't alter the sound quality when it's resaved, even if it's using slightly Mickey Mouse software.
It's slightly different if levels get altered, and it's an integer-based file (16-bit). If you attempt to reinstate any changes made, then you will lose bit depth. The way around this is for all working to be in 32-bit Floating Point, and Audacity claims to be able to do that. So if you want to play safe, save and send files in that format, and make sure the same thing happens with your friend.