Havn't heard the sample, but off hand I'd suggest:
- HPF (standard 6db/octave) starting at around 90hz
- EQ cut starting around 500hz, sloping off about 4db until 300hz, and then just flat (-4db) from there.
Might consider a 2db bump between the range of 2khz-4khz as well.
Adjust to taste but that sounds like what your problem is. I'd suggest doing them in that order as well.