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Based on the page you linked to, it sounds like you have one of those "few" Samsung TVs.
"To hear audio, you need a TV, AV receiver, or soundbar that can decode Dolby Digital or AC3 audio over HDMI. Most modern TVs can do this, though we’ve noticed a few Samsung TVs cannot. All Roku televisions should be able to play audio without any trouble."
It sounds like your choices are to encourage them (HDHomeRun) to "do something about that", buy a different TV, or add a sound system. You probably want to start with the former. I wouldn't count on them reading this forum, though that is possible. I wonder what constitutes "a few".
Personally I'd take this as justification for a good sound system. 
To hear audio, you need a TV, AV receiver, or soundbar that can decode Dolby Digital or AC3 audio over HDMI. Most modern TVs can do this, though we’ve noticed a few Samsung TVs cannot. All Roku televisions should be able to play audio without any trouble.
Roku audio settings:
- Go to the Roku home screen
- Then navigate to Settings → Audio → HDMI
- and change the HDMI option to Dolby Digital
- Go back to Audio and select Audio mode
- and change Audio mode to (Auto (Dolby Digital))
- If you are still having issues, check to see if your Volume mode is set to “off” (this might not always be required, depending on the Roku model) This should correct the audio on Flex Duo and most everything else, Please understand that your Router and connection will play a big part of this being quality video and audio, best results will come with having a series 6 router and ax router preferably. Good luck in your venture, it works wonderfully and I had originally given the HDHomerun Flex Duo a 1 star when it wasnt their problem anyway, it was a Roku set up problem, they will now earn a 5 star rating, as will Roku. Most people dont understand that everything electronic or mechanical will have its bugs, and it usually takes our input to correct and make all of our lives better.
