No stereo audio on Cable TV

[ChrisW6ATV]

This very definitely is a problem with the boxes themselves, not any "bad signal or cable" issue. I have not had pay TV for decades, so I am not sure how a "digital adapter" is different from a "cable box". (To me, any device that connects between the cable/wall jack and a video display is a "cable box" regardless of any fancy name the company gives it.)

If you have one device from the cable company that gives you true stereo sound, then yes, I would try that device in each of your locations, or with each of its available output connections (HDMI, composite/left/right, optical/coaxial digital) to see if they all have stereo audio.

If all of your other (boxes/adapters/DVRs/servers/whatever) have only mono sound, I would suspect either menu settings that are buried in them, or a configuration problem at the cable company where you would be lucky to get access to anyone there who has the brains to understand the problem let alone be wiling to listen to you and/or fix it.

Let us know what you get from your tests.