I am new to power amps so I don't know which brands are better than others. I currently have a Denon 3805, which pushes 120 watts/channel I am driving a 5.2 channel setup of Infinity Prelude MTS's speakers. I want a very good 5 channel amp with 250-500 watts of output per channel. How much of a difference will I notice with the additional power? What amps would you recommend? What prices would I be looking at?