This is something that i've been thinking about in the past few minutes it seems to me that people think that when you put a second cabinet on to your head(amplifier that is not the thing on your shoulders) that its going to be louder simply because your moving more air. Now i think that this might not be a very correct way of thinking. If you had say two exactly the same amps and cabinets beside each other putting out 80dBs each the increase in in the over all sound level would be only two or three dBs if even that although you are moving more air there isnt a huge increase in sound level. From reading manufacturers specs when you hook two cabinets in to your head in parallel(again not the thing on your shoulders)your reducing the impedance and the wattage of the amplifier increases. For example an ampeg B-5R running with one cab at 4 ohms has 350 watts but when you put a second 4 ohm cabinet in you reduce the impedance to 2ohms and the wattage magically becomes 500 watts and i think this increase in wattage is how you get a higher sound level out of your amp with a second cab not because your simply moving more air. So what do you think am i right or have i just wasted my time typing all this out?