Shoutbox

I have a set of self-amplified speakers like these:
... and also a set of poor-condition, original Astone Versa 200 speakers.

After starting to use them recently, I've found that they play music much better if I cut out the lower end with equalisation in my software.

Could I easily build an electronic high-pass filter to incorporate into the speakers (I'm more concerned about the bigger set, not the Astones really), and how would I do it?

Would it be easy to have it adjustable (attenuation, cutoff, filter width/hardness)? Could I add a bass boost?