I was thinmking about getting Sundown Nightshade 18" subs with a saz-3000D amp. But I got thinking. If I have 1 18" sub that will get 3000 watts but if I have 2 18" subs they willl only get 1500 each but there will be more air movement. so I'm just confused which one would be better? I think the 2 18" would be better, but I don't know,.