Audio interfaces just broken on my iMac?
I had trouble getting my Focusrite Scarlett 2i2 to appear as an option in Adobe Premiere Pro CC on a Mac running Mavericks. It showed up in Audition, just not in Premiere.

Go to Audio Midi Setup in the Utilities folder on your Mac (or just search for Audio Midi Setup in Spotlight) and look for Adobe Premiere Pro in the list. There should be a check box to add the audio interface there. Then be sure to quit Audio Midi Setup. I think it doesn't stick unless you quit.

Then go into Premiere Preferences > Audio Hardware and choose System Default Input/Output. This should make it work. It did for me!