Sand is on to something here for you. Start with the available power you have amplifier wise. Some amps can handle 1 ohm loads, and others cannot. Even if you are planing on running 2 different sub amplifiers, the sub question still needs to start there. The key is going to be to match up the correct subs, to correct amplifier, regardless of brand involved. Make sense?

Sounds like this is going to be a nice party once the upgrades are done.

-Brian