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)
I use a MC352 (this amp was designed by Charlie Randall one of the best sounding SS amps they made) with a pair of Dynaudio Contour 3.0's, these speakers are rated at 200watts, I can easily drive them up to 350-400 watts (i like music loud too). One of the best combos I have heard is the MC352 partnered with a high quality great sounding tube pre amp. The MC2300 or the 2500 would make for a fine sounding system indeed!  I went a different route with a tube based pre amp from another company for financial and sonic reasons. MAC dosent make the MC352 anymore so if you can snag one at a great cost I would in a heartbeat.

Matt M
Thanks Matt!  I will check out Dynaudio for sure.

Of course they don't make the MC501's anymore either.  I am just trying to determine if it is worth the extra coin to get the MC501's at about double the cost of what I can get the MC352 for......

Does anyone have an opinion on the Bryston Model T's or the McIntosh XR100's?
I don't listen to music all that loud but have used a variety of McIntosh amps. I did have one MC352 paired with B&W 803D's and it sounded very good. I then got a second MC352 to run the B&W's bi-amped which was even better. Then I went for the MC601 mono's which was the best combination. I think the MC501's would have plenty of power and should be fairly inexpensive since the MC611's are out and two generations newer. I was running a C2300 as a preamp with these amps and thought it paired nicely. I now am using a C1100 pre which I like even better but there is a cost and space factor to use it - 2 units. I use MC2301 mono's now but not sure I would recommend them for continuous loud music.
MC2301's wow!   There are so many choices and I have only recently gotten back into this outrageously expensive hobby.  After reading for what seems like a month straight I still have more questions than 

Everyone seems to say the mono-blocks are always better since they have the ultimate separation.  I look at the 501' like the best "value" (if I can even say that) in the high end Mac amp lineup and have made the plunge.  Now what to do with all of my other amps!  

Will upgrading my C48 really make a huge difference?   Also, back to the speaker question, many seem to think that the B&W diamond tweeter causes fatigue at high listening levels. Is there a better recommendation for harnessing the long & loud sessions that I am likely to have without causing that fatigue?   Watt Puppys?  Revels?  Sonas Faber?  I would like to keep the speakers in the $10K range new or used. 
I run a Mac C2500 into a MC452 to drive a pair of JBL 4367s. The system is very dynamic and clear, no strain at insanely high SPLs. I like it loud also.