The songs that had this problem were FLAC files, and they're almost perfectly remastered, if not perfect.
Yeah true, the vocals are a little recessed, and they're a tad bit too bright. I have IDT High Definition audio codec onboard soundcard.
How do you know they are perfectly remasterd?
If they are indeed perfectly remastered, then that shows you the headphones aren't accurately representing the perfectly remastered music or something else in your chain is greatly affecting your source files in a negative way.