I am considering adding a 15 to my 4x10 and would want to use a crossover to send the lows to the 15. My problem is I do not know how this will work with my current setup. I have two preamps running into a stereo poweramp (one in each channel). When I use a crossover [like the one built into my preamps], however, I will need to use both channels for each preamp. 2 preamps x 2 channels a piece = 4 channels needed. I would rather not invest the money (and weight) into a second power amp. So is it possible to do this any other way?