Did you ever find a fix? It's definitely some type of firmware issue. But seems not so many people have the streambar as they do other Roku devices, so much less feedback from others.
Looking it up, seems others have reported near same exact issues with Roku Ultra (granted that is pushing sound to a TV speaker or sound system...) those users reported toggling the Stereo sound settings to resolve.
However, that isn't an option with the Streambars. Had this unit for 3 months, and it was a little dream was super happy, but then sometime in February (or so...) it underwent a firmware/software update, and now I have this funky static issue. 
I have read a few other forums with users having similarish issues with the soundbar version (larger), as well as other Roku speakers... their FIX was reported to power off the speaker (physically pulling power)... interestingly > that works!
BUT for only about a day (if not less) before it creeps right back up. Seems to escalate when toggling Bass settings along with voice clarity settings, and then seems to just never recover until the full poweroff.
I have a few smartplugs laying around, so probably going to program one of those to auto power cycle my roku streambar once a night. BUT ... really Roku.
I too may call Roku to discuss warranty and/or buy a replacement (cause we already know how the warranty gonna go down... derp derp, they're gonna say 'reboot', it'll work, get off the phone... and then boom # repeat. (At least that's how most go down)
I wonder how many people this is happening to. No one else in my household seems to 'mind it', or even claim to notice it. But it's definitely distorted, staticky ~ and makes for viewing experience to be bad.
Ill def troubleshoot more, and feedback if any success with a better solution. (Outside of physical power cycles)
*Note, software reboots don't seem to fix it, physical unplug does* which is hella annoying and inconvenient.
I guess at minimum, contacting Roku of the issue, would help them determine a firmware update to resolve this issue. Sounds like def software problem.
Boo!
