Mine comes from the username I thought up when I joined Talkbass many years ago. My middle name is actually Miles and I was really into the Miles Davis album Milestones when I started learning upright.
So, miles'tone = tone of Miles (me, not him) because no matter what kind of bass guitar I play, I always sound inescapably like me.
Saying that, this hasn't stopped me from spending a small fortune by ignoring the evidence whilst trying unsuccessfully to disprove the theory! 😂