Ok, finished construction today (well now I guess it would be last night). Two subs, one for roommate, one for parents. Both Dayton DVC 12" drivers in 125L enclosures tuned to just under 20hz with full Adire FP4 port kits. Powered by a PE-300-792 amp modded to 1dB boost at 25hz with a corner frequency of 17hz for the rumble filter. Hooked one up played a little music. Hooked the other up and played a little music. Hooked the first one up again and started playing some Moby. Got to track 6 on the Play album. Turned it up a bit more. Was fairly loud, but not very close to as loud as I expected this sub to be able to go. Then the bass just stopped (no loud bang or clank or any really odd noise). Turned the amp on and off several times. Each time the driver would produce some muffled sound and then nothing again (tried both amps on that sub and the second sub to make sure the problem was the driver in sub one). Waited a bit, decided to pull the driver out again and check the connections. Nothing wrong there, nothing could have shorted. Gently push the cone in a bit. Hear a muffled low click (as well as feel the click) when pushed in a fair ways. Then hear and feel the click again when released back to resting position. Try it free air and get cone motion this time. Still can feel and hear the click when I move the cone. Try hooking up each voice coil individually and running the driver free air. Both coils move the cone and produce sound. After trying both voice coils I try pushing the cone in myself again. No click. Put it back in the enclosure and it appears to be running fine. I was already over an hour late getting on the road to go home so I left. Parents played it for almost an hour with various material and said it sounded great for that entire period. Any idea what happened? Should I be worried about this driver even though it appears to be running fine now?