I am doing some research before I buy a new home theater system. I was looking at buying the M80 or the M60 floor speakers and epic 5.1 system. I was looking to buy an A/V receiver - Yamaha RX-V2600 or Denon 3805 that pushes 120 watt per channel. Would it benefit to have the M80 that can handle 400 watts or would I need a power amp? Would 120 watts be loud enough with the M60s? The sub woofer 350 or 500 -- is it worth the price difference?