If you are moving into a bigger room and can play loudly but still have your system arranged in a reasonably small area (ie you don't move the sofa way back from the speakers) the answer is simple -- get a high quality, big-ass sub and enjoy

If you are going to take advantage of the space and spread everything out further so the distance between you and the speakers is much greater, or if you want to play REALLY loudly, then you're looking at upgrading more of the speakers -- although upgrading the mains to M50 or M60 would be a really good start if you listen to a lot of music.

M60ti, VP180, QS8, M2ti, EP500, PC-Plus 20-39
M5HP, M40ti, Sierra-1
LFR1100 active, ADA1500-4 and -8