Hi. I know this is frustrating, especially since the only official Microsoft answer a few years back was the equivalent of "sorry, you need to get with the times; you're on your own." Unfortunately, all the potential logical work-arounds have been explored
here and in another thread which was linked to earlier. The best fix is likely a hardware one, via buying a stereo to mono adapter or cable at Radio Shack (The Source in Canada) or at a music store. These are what musicians use if they have only a mono guitar
amp or studio monitor, but multiple inputs/instruments (for instance, in busking) but no mixer. They're not expensive at all (although incurring any cost in this instance is a bit infuriating.) I know it's not a "best practice" but I dealt with the issue by
half unplugging the jack, which has the desired side-effect of outputting in mono. My issue was temporary (using a studio monitor instead of computer speakers) so that satisfied me. But I feel for folks with more enduring challenges. There is ostensibly an
Ease of Accessibility section for a reason, but after 25+ years of Windows, none of it takes into account the needs of those with partial deafness. Worse than that, a few solutions used to be available in previous Windows versions, and still are on Macs. Why
on earth they changed the Balance from a single, sliding scale (ratio of left to right) to individual volume channels for L and R, while also removing the mono option from outputs, is beyond me. Maybe they were lobbied by audio software developers who wanted
to offer these solutions on a program-by-program basis, but more likely is that some young jerk MS developers said "screw it, let's just scrap the dumb mono settings to make the old folks get with stereo". Inconsiderate, short-sighted, and typically Microsoft.
=(