better imaging, & soundstaging - especially that holographic disappearing-speaker effect is usually possible w/monitors. if the bass isn't good enuff, use subs - i like 'em a lot, w/subwoofers. but, i like subwoofers - i even ran my full-range -2db@20hz thiel 3.5's to good effect w/subwoofers. look at the retail $135k genesis speakers currently f/a here on a-gon - they're monitors w/subs! ;~)
doug s.