I have an Alpine HU with two pre-outs, one for the front, and one for the rear. I have one mono amp for my subs, and am getting one 4 channel amp as well for the front and rear speakers. The HU has a rear pre-out that can be assigned to a sub out. My question is: What would be my best option in dealing with the pre-outs? The amp has speaker level inputs as well as RCA. Do I use the HU rear pre-output to the sub amp, then the front pre-out to channel one of the 4 channel, and finally use the HU rear speaker wire to channel two of the 4 channel amp? Hope thats not to confusing.