Poweramp alpha build-709, HTC U Ultra, Andriod 8.0 Stock. When the phone is locked, you connect wired headphones and start Poweramp, the Audio output is turned on by Hi-Res, the sound goes through the main speakers. When switching to another Audio output, the sound goes through the headphones, when switching Audio output to Hi-Res, the sound again goes through the main speakers. It helps reboot the device. With an unlocked device, this does not happen. There is no lock as such, just turn on the screen. Maybe it's in the device itself? (Google Translate)
