MC300 MC252 MC501 recommendations based on my setup

So I have 2 systems, 1 downstairs that runs the whole house (4 sets of speakers on a switch) with a C48 and MC252 and Paradigm Signature S8's as the mains in the primary listening area. 
  
I also have a medium size room (large for a house) with a C40 and MC300 on Polk Rti A9's that are just a place holder until I can find the real speakers that I want (Thinking B&W 800 series).  

I like to listen to my music very loud and like to "feel" the music but the MC300 is not cutting it with either set of speakers.  

I have an opportunity to get a set of MC501's and would really like to see what the suggestions would be for a set of speakers that would pair well with them also considering I can move any of the other components upstairs or down stairs to get the best setup in both areas. 
Do I buy another  MC252 and bridge them or biamp them?  Is the MC501 investment worth the upgrade assuming the addition of B&W 800D's later?  How much are the MC501's worth in good shape? 

I have a lot to consider because I am also thinking about upgrading preamps also (interested in a tube pre C2300 or 2500 based on past experience w/ a Vincent MK236) but mainly listen to SACD's in one area and a combination of vinyl and SACD's the other.  (BTW, I also have an NAD M51 DAC that I really like upstairs with the C40)