Use mobile device as audio output for hard of hearing

Background: I’m hard of hearing but can still hear. I struggle a lot with voices. Subtitles are okay but honestly a lot of the story is lost in text. When watching movies I often am yelled at by my wife to turn it down because I have it up too loud. I have to turn it down to the point where I can’t hear the movie.

I know there are devices I can buy that would do this but I already have the hardware for it I just need the software to do it.

So a feature where I could use my phone as a secondary audio output of something being played on my TV (via Chromecast in my case) would help. I would wear headphones and have my own volume adjustment so I can hear and my wife won’t have to yell at me.

IMHO, this is a nice idea.
However, it won’t materialize from within Plex. There are too many problems to solve, which lurk within this approach. Synchronicity of picture and audio being the main one.

Faster relief (i.e. right now) you can get with a full-on hearing-aid (pricy, no doubt) or wireless headphones (a little less pricy).

Early 2021 clean-up: duplicate