Best upgrade path from Borresen X3s

Well, i suppose you could get yourself a pair of ....say Wilson Alexia Vs for about 70k. Set it next to your X3 and start comparing. Determine what beat out what after equalizing the caliber of electronics used for both speakers.

Later on/an year later, try selling that Alexia V and see if you can get 30k for it. If 3k is a big deal, a 40k Alexia loss could hurt the feelings a lot more, i’d think..

I'll just add my voice to those who have asked what the OP is trying to "improve."  You'd think for the dollars in play that one would be able to identify some specific traits in the current setup that are weak compared to what he would like.

Something less aggressive and smoother sounding ?  E.G Spendor Classic or D9.2.  

A room your size would really benefit from a swarm sub array.  Will definitely make your x3 sound much bigger/fuller.