Hello, as I was reading through this I think I understand but want to make sure I am correct. From my understanding, Can the "Line Out" on the Home Receiver be used in the same way as the "Line Out" in a aftermarket radio for a vehicle? Meaning for a vehicle subwoofer you connect the subwoofer to a amp and the amp to the Line out of the aftermarket vehicle radio. For the home receiver that has a single rca connector for a subwoofer meant to be connected to a self powered home theater subwoofers. If the home theater Receiver has a line out, could you connect that to the same amp and subwoofer set up you would use in a vehicle?
If the receiver has a variable line level output then you could connect a powered subwoofer there.
It would be better to use the subwoofer output because then you would be able to set the L/R front speakers to small (with the sub output turned on).
That would remove bass from them (which using the front pre outputs would not). They would play louder and put less strain on the amps in the AVR.