I was having some strange problems with audio not playing back properly in After Effects the other day, followed quickly by a similar issues in Premiere Pro. Wasn't able to find any google love for the problem, but eventually stumbled upon something that seemed to have fixed my problem.
Basically I was occasionally losing the ability to playback audio during Ram previews in AE, no matter what I had the audio preferences set at. I think* my problem was solved after booting up the 'Audio MIDI setup' utility. In here I noticed that there was entries for both After Effects 10.5 as well as After Effects 10.5.1, which I think was the route of the problem. Maybe the 10.5.1 update left some cache or something that was causing a conflict? Either way, I deleted the old one and everything seems to be back to normal for me now.
*Not 100% sure this was what solved it, but I'm pretty sure as things seem to be remedied for the most part now. This may or may not be of any use to anyone, but I just thought I'd put it out there in case someone stumbles upon this in a google search, as I couldn't find any mention of it out there myself. The Audio Midi setup tool is in your Utilities folder fyi.