I would think the Energy rc 70 would do fine with the Marantz SR 6003. According to the specs. which are not the most comprehensive, it looks like it doesnt take a whole lot of power to drive the Energy speakers. You never know however, till you get there.
http://www.energy-speakers.com/na-en/products/rc-70-specifications/
http://www.energy-speakers.com/na-en/products/rc-70-specifications/