I was within 24 hours of giving my Pro-HD away to a friend to use as a desktop player and WD TV streamer. It was simply unusable on iPhone or iPad/Android because of the distorted audio.
Today for the first time since I bought it, I can use the App without cringing and turning it off because of the tinkling echo which has been a reported problem here for more than 4 years.
It is still there slightly, but I get something similar on my other streaming devices.
For the most part, the Pro-HD works well for the first time on my Sony Experia tablet - thank you Sling.
The new App (Chromecast version) looks great and while there is more work to come to rid the audio echo totally, my Pro-HD is working better for the upgrade.
Pro-HD users, I'm interested in others' audio experience who have had the tinny echo.