100-120 is too high, should be more like 80. Also its much better to run the mains full range. There's nil to be gained, all the talk is just that, talk. On the other hand there is much to be lost. The main factor in good bass response is lots of low bass sources. Crossing over the mains removes their contribution to low bass and so actually harms your bass response.
You're taking something super easy and complicating it every which way. Leave your mains alone. Put your two subs near different corners, do NOT set them up symmetrically, set them to 80 Hz adjust levels and enjoy. Then go shopping for a couple more subs.
You're taking something super easy and complicating it every which way. Leave your mains alone. Put your two subs near different corners, do NOT set them up symmetrically, set them to 80 Hz adjust levels and enjoy. Then go shopping for a couple more subs.