That is what I thought also. I was talking with a guy on the phone from audiocontrol he told me that the lcq1 does not have a crossover built into it. I would have to use a separate one or the one built into the amp. I would have to do that if I summed the channels. The sub output would be used if I sent the factory sub signal into it. That signal is already crossed over. I would use the same crossover settings the factory speakers are at which are not optimal. If I summed them I would use the full range out and split it again with a crossover. At least that was my understanding from talking to them. They also think I should try keeping the factory signals separate first. As it would be easy to later sum them. Since it would just be changes on the lcq1 and all the wiring would already be there. But I don't know yet.
The 8w7 would be getting 300rms from the bridged back channels of my amp the spz60s will be getting 150rms each. The jl 600/4 puts out the same power as long as the impedance is not below 1.5 and I forgot the top number. By bridging the two channels for the sub it would see 300 at the 3ohms for the sub.
I am just looking for a sq system that will have a little bit more volume then the factory one. Clarity is paramount for me. If I am incorrect in my thinking please let me know I need all the help I can get with this one. It's not like my other vehicles where I could just rip everything out and use aftermarket everything. Thanks.