I too think the z560's emphasize way too much the bass, this is not a problem that a simple equalizer (winamp) can't fix when playing mp3's and such. Can't you just run your music through an equalizer? I've also noticed that moving the sub around to different locations effected the sound greatly - this might help. I remember one post about a guy who was going to open up the sub and stuff some polyfil into it, to dampen the bass, the sort of stuff that car audiophiles do to their subs, I guess people to this for 'muddy' bass? Don't know if that's correct, I might try this one day.
-VTrider