Aha!!
So- it's a 'standard option' in the player menus, eh?
I shoulda checked that! DOH!
As with many other options, there must be different 'home' and 'car' settings.
I'll unplug my amp so I can run the player in the car without having to subject my ears/neighbors to the 0.0dB setting while I sort out the problem.

THANKS VERY MUCH!!