that's the so called :) -curve. :lol: standard setting everybody does on a home stereo. :lol: :lol:
i think a slow slope from kick/bass to the highs looking like a 'ski ramp' is what is generally looked upon as a good freq. balance.
in the izotope ozone mastering guide it's called the 6db rule...
gaps or holes in the spectrum aren't a good thing, i think.
you can fill the parts in the midrange up perhaps with a pad
and/or a percussion loop. don't try and fix it on the master, fix it in
the mix as good as you can!