is your room treated, can you listen to these speakers in a different room and hear same muddiness? i dunno these spkrs. but if you are still driving them full range plus adding a sub at 80kz then heck yeah you got a chance of having excess crap at that octave. have you always noticed this and are you driving them hard? just a few thoughts. if you are x-ing over at 80, to me that is too high for most non cavernous rooms unless you have tiny monitors