It would be ideal if you list down some key information so that people can guide you.
-The model of the Marantz amp.
-The size of your room?
-Floorstanding or standmount speakers ?
-What are you missing from the current setup in terms of your expectations ? Or what are you hoping to gain with the upgrade ?
-Budget
Information like this will help people to guide you so that the needle moves in the right direction in terms of value and satisfaction for you.