It's true but there are a bunch of little caveats. How big are the drivers, at what volume are you listening, headphone impedance, etc...
These days it really don't matter. Phone have ample battery capacity.
These days it really don't matter. Phone have ample battery capacity.
...are you sure? And, is that still true even once you consider the extra encoding the phone’s CPU has to do?
I was under the impression that conventional 3.55mm jacks output exceedingly little power...