does the logitech have any software? if so it may have an equalizer. i would suggest lowering the left side of the equalizer which should cut out the bass.
if it doesnt, you can always get an equalizer program for windows and use that and do the same thing. this came up in a quick search http://sourceforge.net/projects/equalizerapo/ but i'm not sure if that is the best one for you or not.
Your computer probably has Realtek HD audio manager,if you open up the sound manager and go to sound effects you will be able to press the graphic EQ button then if you drop the left three sliders it will cut the bass,just play about with them until it sounds right.