Slightly blend stereo audio to support partial deafness I'll try to explain my use case and what I think the solution is that I'm looking for. However, I'm open to options.
Situation - I'm mostly deaf in my right ear. I can detect sound in my right ear but cannot make out what's being said. My left ear is fine. When using headphones I'll find that during certain videos the content creator decided to put some or all of certain track on the right channel. I know this because I can detect the muffled sound in my right ear but cannot decipher the words.
Possible solution #1 - Accessibility feature of MacOS which turns stereo into mono - I've tried using this feature, and it does work. However, I lose the pleasing effect of stereo. Even being mostly deaf in one ear, it's still possible for me to enjoy the benefits of stereo music.
Possible solution #2 - Don't use headphones - Due to my work situation headphones are required
My ideal solution would be to just slightly blend the right channel into the left channel. I was hoping Mac's accessibility feature would have a slider but as far as I can tell it's an all-or-nothing selection.
Does anyone know of a method to do this?
Thank you!
The app to do this for any or all apps or outputs is Rogue Amoeba's SoundSource
This can route any app to any sound device, with EQ… or more importantly, any AU (Apple Audio Unit) Plugin.
macOS comes with a selection of these built-in, but unfortunately not a simple balance/stereo width plugin.

Searching for freeware plugins, I found a discussion at https://community.audirvana.com/t/channel-balance-controls-au/10605/15 recommending some, from which I think Airwindows EveryTrim or Flux StereoTool might be suitable. The trouble with both these is they're just not as straightforward as they could be. They're designed for audio pros. If you struggle, then maybe there's a simpler tool out there… I just can't find one right now.
i found some more listed here - https://www.kvraudio.com/forum/viewtopic.php?t=408421
What may help - depending on whether your hearing loss is broad-spectrum or above a certain frequency range, is to push some 'treble' into one side but not the other.
An earlier app from Rogue Amoeba, Audio Hijack does actually come with the plugins necessary to do this stereo/EQ routing, but it's more expensive &amp; it isn't a 'global' solution, it's more one-app-at-a-time.
I answered an earlier question at the time using Hijack - Mono output from an external DAC and also this one - Split Input Channels Using SoundFlower and AULab
I'm just trying to see if installing the demo of Audio Hijack would put those plugins in the Mac's AU folder so you could use them from SoundSource…
… No. Apparently they're internal to Audio Hijack.