Volume at 15 is really loud if you're in a quiet home and maybe not enough if you're in a busy street with cars honking but you have an additional 15 steps and at 30, you will damage your ears with prolonged listening. Total volume is the same as in Pie but you have twice as many steps.
For someone with tinnitus that just want a distraction in their quiet home. Setting the volume to 1 or 2 with music is perfect.