I'm both posting an issue I'm having and a workaround for it. I've already contacted Roku about a software solution but they've done nothing about it so far. And it's so easy.
After using the Roku for a number of weeks you discover the audio is either out of sync, crackling, or both. I don't know the source of the problem but have a suspicion. The workaround is simple -- unplug the Roku, wait 3 seconds, plug it back in -- fixed.
WHY THAT WORKS
I own the Ultra and it only has 1 GB of RAM. If you've ever had a cellphone with 1 GB of RAM it will run like garbage in no time at all. The only fix? Reboot. The reboot frees up all the RAM and starts everything all over again.
SUPER EASY FIX
Roku needs to add a setting. Where restart is the option for a nightly 4AM automatic reset.
Please Roku. Add this feature. I have to get up and unplug and replug my unit about every two weeks. Very annoying.
By the way -- other issues people are experiencing might go away with this same fix. Right? Because whenever you talk to a tech about your PC or phone -- what's the first thing they tell you to try?
10 MONTHS LATER UPDATE
The solution I use now requires an Amazon purchase. It's called an Etekcity Vesync Smart Plug. The smart plug has a programmable timer you control from your phone. So my Roku loses power around 3AM and doesn't come back until around 4PM. (See it how you like.) This is an inconvenience and small expense, yes, but since you end up buying four of these things you may want to use them elsewhere in the house. (My wife and I never turn off our downstairs lights anymore. We let these devices do it.)
Any magic trick to the reboot? The crackling just started on our television when using the roku. We tried switching the audio to stereo. Restarted. Tried rebooting a few times. No change. There is no cracking sound when on regular TV or when using the earphones.