Earlier quoted context omitted.
It is still impossible to change audio volume for headphones before the app begins playing. Consider this scenario: - Use iphone at max volume to power speakers (pseudo line-out) - Switch to sensitive IEM's later, attempt to change volume before starting... can't. Just changes notification volume. - Begin playing music, rupture eardrum if IEM's in. Fortunately iphone doesn't push enough current to damage the hardware…
(There is a setting in Settings that will turn off ringer volume changes with the buttons. That way you will always adjust the volume and never the ringer, no matter whether anything is playing or not. As such you can then adjust the volume of headphones without playing anything with the buttons. Works like a charm. I find that I personally never need to adjust the ringer volume once I have set it to an appropriate l…
Thanks for the tip about ringer volume though. Creates a new problem but at least it's not a problem that involves hearing damage.