I have a MAC Mini & a MacBook both running Sequoia 15.3.2. Neither will play anything out to my USB interface. Funny enough my IPAD works, but not the MAC. What am Im missing here?

What interface are you using.

You need to switch the system sound output in macOS to your audio interface.

well, got it working today in 5 minutes. I was missing something before. Thanks and looking forward to 4.0!