I think I drove this sub too hard. Now when it's turned on, all controls down, and no input, all three drivers oscillate at around 60 Hz. It starts quiet, then gets much louder until it maxes out on the volume. I'll get it to the shop this week but unless its a fixable issue it looks like it's fried. I know it's impossible to diagnose something like this with the info I provided but I'm open to ideas. I opened it up and looked at the board. No apparent blown parts or burnt traces. Any info would be appreciated.