Route audio from different programs to left or right speaker and left or right headphone

Request
Would be great to have something that could route audio to the left or the right speaker (and/or left or right headphones too).
If there is an equalizer that would be great too.

Why
Many of us have numerous things going on at the same time. Background music while also watching a documentary might be one example. For myself I have multiple audio going on when I study a language. I get around this by using the phone and computer in tandem but would be great to have this simple feature in the toolbox.