BookShelf Speakers Sound Muddy HELP

I have a pair of Sonus Faber Concertos (not the domus). I also have a Vandersteen Sub. I notice that the bass coming from the speakers sounds a little muddy. The highest crossover setting on the Vandersteen is 80. Is there something I can do to tighten up the bass on the Concertos. Could this be a placement issue? I have the speakers on stands about 18 inches from the wall.
The speaker are coupled to a hardwood floor with spikes and floor protectors.
I would suggest bringing them out into the room some more.
How close is to close? If I brought them out any more then I would be less then 6 feet away?
Are you running the main speakers full range?
Turn the sub off and listen to the bass. If it's not still muddy sounding, then either placement of the sub or level is too high. Probably level matching. Did you use test tones and an SPL meter?
Could be crappy speaker stands too. This just happened to me.

Perhaps you expect too much from small speakers - I mean the bass and midrange come from the same small woofer. The idea of litlle speakers like this with gorgeous finish is mainly aesthetic and it is really a bit unfair to expect too much in terms of bass quality from a small ported box. Great speakers but you can't "have your cake and eat it" so to speak.
Would I gain a benefit by buying an external crossover and cross over at a lower level 65 as opposed to 80?
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