If you prefer to match the brands of Pre-pro and Amp, and you don't want to buy another McIntosh Pre-pro, then sell the Mac Amp.
If you don't care to match brands (which is unnecessary), then you can just buy another pre-pro.
It also depends on how much you can get for the Mac Amp.
As far as which pre-pro, AVR, or room EQ is better, that all depends on whom you ask because everyone feels differently.