At 300w you should have enough power. What's the peak power rating on the Plinius? I am using an NAD Masters M3 rated at 180w on 8ohm-dynamic power of 280 watts at 8 Ohms, 480 watts at 4 Ohms, and 785 watts at 2 Ohms. Though many people will tell you that is not enough power to drive the C5 it is b.s..It is enough power, but everything else needs to be right ,too. You have to place the speakers right, you need very good cables, power cords, interconnects and speaker cables that don't loose signal strength. It tried a bunch of different cables to reach sonic bliss with my C5, but it was worth it at the end, despite manny years of frustration trying to figure out what they needed to sing right ;-). Try PCOCC based speaker cables, they deliver fast impulses, a punchy bass which is needed for the C5, and a beautiful silky smooth revealing high end frequency range. Cheers,