. I've read that aptX offers "low latency" but what exactly does that mean behind the commercial talks. Low latency might be perfectly fine to listen to music but still way too much for a movie.
With a stereo mixer, you could optionally mix the left & right (pan both inputs to center). That might be better since your father's brain is used to hearing an imbalance.
Low latency (delay) is good (with video). Wired headphones have zero-latency* (as would any analog wireless transmission). With music only, of course a few milliseconds of delay is OK, but with video you might start to see "lip sync weirdness" around 100mS or so.
Now you got me lost. How is panning the left/right sound different from changing the volume? Can you really "move" the sound around? Does it involve adding sound from the left channel to the right one (or the other way around)? Now that i think of it stereo might be an issue as he might miss the sounds that comes to his bad ear with headphones so i might have to turn the sound to mono.