Its really quite simple. How is the Audioengine app connecting to the My Cloud to access the music files? Does it use SMB/AFP? Or does it use DLNA or iTunes connection? If the app uses SMB/AFP then one should be able to turn off Twonky and iTunes in the My Cloud Dashboard > Settings > General page. If the app uses DLNA or iTunes then you will have to have Twonky or iTunes enabled in the My Cloud Dashboard > Settings > General page.
To hear the music from files stored on the My Cloud you need something to access the files on the My Cloud then play that file through speakers or headphones. The My Cloud is just an NAS that has media server built into it. Generally a media server on an NAS requires a media CLIENT (a computer, mobile device, or other electronic device) to access the media files and play the file through speakers or headphones.
As a basic troubleshooting step use another media streaming app and see if the issue persists. If it doesn’t then its a conflict between the Audioengine app and the My Cloud. At which point your best bet is to consult the app’s maker to see if they have any suggestions.
When using Twonky its a good idea to review the big Twonky FAQ that was put together by a user here:
[FAQ] Twonky DLNA Media Server Setup & Use
