iMovie won’t play audio through interface

Try these diagnostic procedures:

Deleting

Preferences

Try opening iMovie while holding down the Option and Command keys and selecting to delete preferences in the box that

appears. iMovie will open in a new library. Reopen your old library to get back to your projects. Now see if iMovie will play the sound.

Safe Mode

You could also try booting up in Safe Mode (see Finder menu for instructions) and, after everything loads, immediately shut down and reboot in normal mode. Then see if iMovie works properly.

Updating iMovie

To update/redownload iMovie 10, drag your iMovie 10 app from the Applications folder into the trash, but do not empty the

trash. Sign in to the app store and open your purchases folder by clicking on your name at the bottom of the app store side bar. You will see your purchases displayed, including iMovie 10. Redownload/update iMovie from there. If not successful, drag your present iMovie app out of the trash and return it to the Applications folder.

Resetting the System Management Controller

Try resetting the System Management Controller:

https://support.apple.com/en-us/HT201295

Resetting the NVRAM or PRAM

Try resetting the NVRAM or PRAM, although this issue would be fairly rare:

https://support.apple.com/en-us/HT204063

Hi,

Since the iMovie audio output works everywhere except with your Universal Audio interface, it does not appear that the issue is related to a bug in iMovie. I'm thinking that it might have something to do with the Thunderbolt connection to the Universal Audio interface. Their website shows that it can be used with Thunderbolt 2 or 3. I believe that your iMac 27" has a Thunderbolt 3 port so if you are using that it should be working O.K. You might try switching to another Thunderbolt port, if your iMac has one, and see what happens. Or perhaps the input port on your Universal Audio has some issue. I'm just speculating here.

Also, you might want to try posting your question in the UA forums. They have a troubleshooting section. Here's a link:

https://uadforum.com/forum.php

-- Rich