I didn't get a chance to read all of the above comments but I will tell you to check the phase. Use a nine volt battery and a small wire lead, touch the leads to the speaker wire at your amp (disconnect them from the amp first!). The positive lead of the battery goes to the suspected positive and the negative to the negative. If the sub moves in the leads are backwards, if it pushes out it is correct. That will give you a definitive answer as to the phase of the speakers, just make sure to test all of them. Then of course there is the possibility that you blew them up and they need replacing. Also the positioning of the speakers in the room can make a huge difference as well. So if they were to much up against a wall, and to little when pushed away. I would push them back towards the wall and raise them off the floor.
I hope I helped,
Andrew
Synesthesia Studios
I hope I helped,
Andrew
Synesthesia Studios