Try pushing on them with your hand on the cone (don't need to hard though!). If it 1: doesnt move or 2: crunches/pops a lot then chances are you blew one... I had a pair of kicker comp 12s for my first setup and I ran them off an OLDDDD JL amp that I believe was 1000 watt max but that was 6 years ago and a lot of setups ago... I didn't blow mine and mine were in a sealed box. I'd try to push on the cone with your hand and subs off. You should atleast be able to tell if one (or both) messed up.