I think the best option for you is to sell the Marantz. You need power for the Pl-300.
You need to spend some extra money on an amp. Based on the fact that you do not have a lot of knowledge I will give you some advice you can use for yourself.
Primare A32 and Pre30 is a very good option. To contol the Pl-300 and to create a deep and wide stage.
Pathos Inpol-2 is also an option. You need to see for a used one. This one cab also create a 3D stage with the Pl-300
You need to spend some extra money on an amp. Based on the fact that you do not have a lot of knowledge I will give you some advice you can use for yourself.
Primare A32 and Pre30 is a very good option. To contol the Pl-300 and to create a deep and wide stage.
Pathos Inpol-2 is also an option. You need to see for a used one. This one cab also create a 3D stage with the Pl-300