Skerdi, I think a STEREO GRAPHIC EQUALIZER would do the trick. You could pump up the mid-bass for warmth and cut the sibilant frequency which is below what the usual treble tone control covers.

Check the link below.

http://www.crutchfield.com/S-PnOc4Hy4stC/cgi-bin/prodview.asp?i=024EQ200