Upgrade A/V Receiver or get 5 Ch. Amp

Hello folks!
I’m in a little confusion here. I have Rotel RB-1582 MK II running B&W CM 10 S2s as main and a Marantz A/V receiver running my CM Center 2 S2 and CM 1 S2s for surrounds. I know the power from the Marantz (125w/ ch) isn’t good enough for my centers. I’m thinking to upgrade, but confused on which path to take first. Either get a new receiver, ie. Anthem MRX 520 (100W/ Ch) or get the Anthem MCA 30 or MCA 50 amp to run the center and surrounds. I I plan to get both over the time but for now I’m confused as to which one to get first. Or I may get a processor, AVM 60 rather than the MRX 520 or 720. P.S. I live in a town home and I don’t see myself moving to a single family with a theater room at least in the next 2 years.

Thanks!