You guys will all laugh at me, but I 'normalized' the tinny crap
speakers in my 1980 Ford Fairmont by pulling the speaker grilles off
and sticking a rubber mat to the back side of it.

When I put the grilles back on, all the really 'sharp' treble was cut,
and the speakers sounded a little more flat.

I couldn't tell you any numbers or anything to that regard. I guess I
was just lucky.



In your case though, I would agree with the suggestion of a graphic EQ.
This will let you dial it in exactly like you want it, and even let
you 'adjust' it for certain CDs, like those that are all compressed and
clipped to hell.

Good luck.

-phaeton