You'll need to grant Tasker (paid, 3rd party app) adb permissions via PC (search tutorials online) or with the LADB app (again, search tutorials for this)
It's a one-time thing, so I strongly recommend doing most or all of the permissions in the extensive list below so you don't ever have to worry about Tasker permissions. I've forgotten the exact one you need for this specific process, but you'll be reminded in the Tasker app
https://www.reddit.com/r/tasker/comments/e2mjzk/adb_additional_permissions_list/
Here's the task: https://taskernet.com/shares/?user=AS35m8m6PdaeVocfnxwaBxRIYGws0vmj%2Bns010SyLgBwWCOHchmIhh3BULofUd7uSuOTDgy9AA%2Fkg0U%3D&id=Task%3AUnload+Poweramp
Under Profile tab, create a new profile, select 'Application' type, leave only the Services box marked, and select all the apps you don't want Poweramp overriding.
That's all.
Let's hope that when the dev has the time, he can implement this into the Poweramp, so no need for Tasker. Fingers crossed.