Peace extension has very good youtube videos.I had a quick look at those links but it seems to be over complicated for my needs
I tried APO but it just would not work with my setup (yes, I tried a lot of troubleshooting options and googling).
I ended up buying Boom3D and it. just. works.
Very happy - can finally get the balance right between bass / mids / treble. Since I'm just using a budget-ish 2.1 setup, the mids and bass are much too heavy and treble lacking.
Music sounds like it should (or damn close) to my Sennheiser SP25 / NAD / Dynaudio setup.
APO is a faff and there are many reasons it may not work, or is so confusing to people that they understandably get lost..APO is system wide. Not sure how it couldn’t work.
At least you found something.