Editing and mixing should be done at levels you can hold a comfortable conversation over through speakers that are as flat as possible and use your interface for monitoring as well as input the D/A converter is much higher quality that your PC motherboard.

Many soundcards are optimised for gaming etc so won't give you the flat response you need.

Your meters are only a guide, your ears or many sets of ears through many sets of speakers do a better job of finalising your mix.

A/B your mix with a commercial CD that has the sound you are looking for.

It's not a black art just good listening and knowing what your plugins do