HLE wrote:
Good questions.
It's an HP P3 subnotebook running WXP Pro, with an ESS Maestro 3
"sound card" (chipset, I guess). As though it matters, the headset is
binaural, by Plantronics, and has excellent quality and sensitivity
(106dB/mW or better, with big diaphragms).

I want this to be done in software because of portability issues.

You might want to try these:

http://headwize2.powerpill.org/projects/anwida_prj.htm

http://www.digitalfilter.com/realeq/realeq.html

http://www.ezetest.com/acd/adeq.htm

I have no personal experience with them, but they look like possible
solutions