There is no such thing as having too much power.
The biggest danger is not having enough power; you may end up running your amp too hard and clipping occurs and speaker damage occurs.
Your second question: Doubling the wattage increases volume by 3 db.
My speakers sensativity is 93 db/watt. They are capable of 120 db at 3 meters. I have 1200 watts per channel. Will I ever use all that power? ... NEVER! ... but my sound is wonderfully clean, and there is no chance that I could ever drive the amps to clipping.
Richard
The biggest danger is not having enough power; you may end up running your amp too hard and clipping occurs and speaker damage occurs.
Your second question: Doubling the wattage increases volume by 3 db.
My speakers sensativity is 93 db/watt. They are capable of 120 db at 3 meters. I have 1200 watts per channel. Will I ever use all that power? ... NEVER! ... but my sound is wonderfully clean, and there is no chance that I could ever drive the amps to clipping.
Richard