Optimal Volume Levels?

Message: Hi I have looked all over the internet for years now and I have yet
to find an answer to my question: At what levels do I set my Windows Volume
controls to ensure OPTIMUM sound processing/quality. For example, I play
music through iTunes on my PC. I always have the ITUNES VOLUME at maximum
level, along with its equalizer set on rock. In WINDOWS' Volume Control,
however, I'm unsure about what levels the WAVE and MASTER sliders should be
adjusted to ensure optimal sound quality. Can someone please provide me with
their professional opinion about the best configuration for my playback
volume?
SOME OF MY UNCERTAINTIES:

FOR MAXIMUM QUALITY, SHOULD THE "WAVE" SLIDER BE AT ITS MAX EVEN WHEN
CHANGING THE MASTER VOLUME?

OR, WHEN ADJUSTING THE OVERALL VOLUME, IS IT BEST TO ADJUST BOTH "WAVE" &
"MASTER" SIMULTANEOUSLY (AND AT EQUIVALENT LEVELS) FOR MAXIMUM QUALITY?

AND LASTLY, IF I WERE TO HOOK UP EXTERNAL PC SPEAKERS, WHAT CHANGES WOULD I
MAKE TO THE WINDOWS' VOLUME CONTROLS -AND- HOW SHOULD THE SPEAKER'S VOLUME
KNOB CHANGE WITH RESPECT TO THE WINDOW'S VOLUME CONTROLS?