I've tried every music app on the play store to find one that will do most of what I want and Poweramp fits the bill. However I cannot launch and audio files from the android explorer or any other apps, This would not usually be a problem as I could just enable google play music or install another audio app that will do that. However as soon as I install any other audio app, it breaks Poweramp's ability to work Bluetooth in my car. What happens is: Poweramp no longer responds to BT controls from my car, does not autostart or autopause, and does not send metadata to car display. If I play something on Poweramp when it's connected to my car it will play but none of the controls will work.
Once this happens, the only solution seems to be to remove all audio apps, disable google play music restart the phone then reinstall Poweramp let it sync the media and then restart Poweramp.
Is there a permission I need to set to enable Poweramp to be launched by other apps and play audio files that are sent to it?