You have something setup wrong then as mine does DD+ from Prime without any issues.
https://support.roku.com/en-gb/article/208756108-does-the-roku-player-support-surround-sound-
[RB];30453192 said:Hi Easy,
Sorry for the thread-necro but wanted to check how you were getting on with the Roku 3?
I'm currently in the market for a new 'all-in-one' solution for pretty much the same needs that you've listed above.
Does it cope OK with larger MKV files (30GB+) via Plex?
Also, have you tested wireless vs wired connectivity to see if there's much difference?
Thanks in advance.