renojim I ask my son to try his Roku remote with his TV's speakers vs his soundbar, and he'll let me know this evening after he tries it. Trying his remote isn't practical as he lives 1,300 miles away.
Tivoburkee I realize now I erred when stating my son and I had identical set-ups. While my TV and soundbar are Samsung/Sony respectively, his are Panasonic/LG. I also failed to mention earlier I have an Xfinity cable box connected to my TV via HDMI as well as the Roku, and but my son only uses TV/soundbar via optical cable and his Roku. My normal method of powering on the TV is with the cable box's remote and then I use that same remote for channel and (soundbar) volume selection. To use Roku, I press the Home icon button on the Roku remote and then use that remote for all but volume selection (I still have to use the cable box remote for volume).
Because it sounds at this point that my Roku remote's volume controls won't work with my set-up, I'm disappointed that Roku doesn't provide such disclosure/stipulations on their packaging or anywhere in their instructions that I can find. Although it wasn't much, it appears I needlessly spent extra money for the voice remote which will only serve the same function for me as their simple remote. I turned to this Roku community forum after too much of my time wasted trying to get this working (including a frustratingly unproductive session with Roku's online chat "support", and I appreciate the responses.