Sorry, I don't use windows, so I'm not familiar with that
software. I like to use sox for bass rolloff. It has a nice
gentle 6db per octive highpass filter. You can get it from
http://sox.sourceforge.net - There is a windows binary
available.
I usually rolloff at 100 or 80 hz. If it is really bass
heavy, I run it multiple times.
sox infile.wav outfile.wav highp 100
Btw, I grabbed 4/17/06 from Dime last night. That is realy
sweet!