I was thinking maybe it has to do with 0-63 being 64 numbers which could be a small convenient bit storage. But that's 6 fucking bits which as far as I know nothing really stores in values lower than a byte. Maybe there is some chip somewhere and 6 bits are used for volume and the other bits are getting used for other things. It's still a very weird value to have
120 has a lot of factors. It's a good number for a lot of situations. But IDK why it would be desirable to be able to set the TV to one sixth of its max volume when sound doesn't scale linearly anyway.