Here is the deal. I have been running bookshelf speakers of various sizes and brands for a long time. The last ones I have been using are Polk Monitor 40s. Today I picked up a used pair of Infinity SL50s. 92 dB sensitivity. My first "towers". Great deal. Anyway, I am finding myself having to turn the volume way up past where I was comfortable with the bookshelves to get the same room filling sound. My reciever is a Denon 1802 rated at 80 wpc. How much higher in wattage will I have to go to notice a big difference in volume? Do I really need to double my wattage per channel to get a 3 dB increase in volume?