On a headunit with only two preouts, what is the BEST way to go about hooking up a 4 channel amp and a subwoofer amp? I realize I have two options:

1. Use Y cables to split front signal into two signals, and use the rear output for subwoofer

2. Run front and rear outputs to an external crossover with a built in low frequency splitter and Sub-output.

Thanks for any input.