Well I tried this, I dropped 6 bands from the right, to 0 on the 31band. On any flac song the treble was missing, but on all mp3 songs they sounded just fine, until I turned the treble knob all the way to 0. And I have 2 of the same song on flac and mp3 that it was tested on.
Athlon 2800 512ddr, auzentech x-plosion pci card, asrock k7s41gx mobo
edit: by 0 I meant the lowest they could go, -10db I believe