I know I said I wouldn't help you anymore but this is what I was trying to explain. if you run a 4 channel on two sets of components you can devote two channels to mids+highs, two to bass. Most decent amps will allow you to do this (hpf for the front, lpf for rear or vice versa). The problem comes in when you use an amp that cannot handle the lower load (2ohm usually, depending on what impedance the comp.s you're using are) and it goes into protection to save itself from burning up. Most good amps are 2 ohm stereo stable so you can put a 2 ohm load, for ex. On the two front channels, where you'll have two sets of 4 ohm comp. The thing is with this type of setup you'll lose either fade or balance because you only have inputs for two channels. You really won't end up with less power either, most amps that are 2ohm stable stereo will gain power but lose stability at lower impedances (I'm sure you know, but ohm is a unit used to measure resistance, so as resistance decreases power increases) so say you have an amp that does 90wts per channel @ 4ohm, put the amp in 2ohm you now have (for ex.) 125wts or 180wts per channel.