Let's say I have two bass combos that are the same in every way except that one produces 100W and the other produces 200W of power. Common sense tells me that the 200W combo is going to be louder than the other one, although not twice as loud due to the nonlinear relationship between power and perceived volume. However, it seems that 100W would be more than enough power to move the speaker cone to its maximum excursion, especially if the sound being amplified had a lot of very low frequency content. Maybe this is where my thinking is off, but if not, then how would the 200W amp manage to generate a higher sound pressure level from the same speaker? On a related note, would you generally get more volume by increasing the amount of power driving a bass cabinet or by adding an extra cabinet to an existing amp (assuming you couldn't do both)?