typically, the lower the impedance, the more straight through power there is (in layman's terms). You're more than likely not going to have a 2 channel amp at 1 ohm each, usually 1 ohm is only for mono or bridged applications. All that means is, there is less resistance from the power source to the load, or the amp to the speakers in this case. You want a clean power source and the least amount of resistance in getting that power to where you want it, to your subs.
It's not that there's more power with less ohms per se, it's more that the amp and sub companies can make a more reliable product when there is less resistance to get the power to the sub. You can have a cleaner sounding 2 ohm sub with sufficient power than some 1 ohm stable subs for instance. Impedance shouldn't be the only thing you're looking for.
