My basic question is which head will be louder/more powerful. I don't really understand how biamping works, and I don't really know a whole lot about ohms other than the lower the better, that every cabnit you add after one splits the ohms in half, and that you generally don't want to get below four ohm's. So that being said, what would be a better said up, as far as power goes with a Hartke 2x15xl and a Hartke 4.5xl? Either the HA5500 (500 watts mono at 4 ohms) or the Hartke HA7000 which is 700 biamped? The HA7000 also has an adjustable crossover which would be nice. Thanks!