Sieht mit Audio Support ja noch nicht soo gut aus:

Native Instruments - Not supported and advising not to upgrade.
PreSonus - Not supported and advising not to upgrade.
Avid - Yosemite is not supported at this time.
Waves - Official Waves OSX 10.10 Yosemite support is planned very soon. We suggest Waves users hold off on updating at this time.
Universal Audio - Not tested yet.
iZotope - Mixed results, see specific information

http://www.pro-tools-expert.com/home-page/2014/10/18/os-x-1010-yosemite-official-compatibility-statements-so-far.html