I have a BTA6100 connected to the HU with the Fast-9999 harness (high level inputs). I'm in a truck so I usually keep the gain at a low level. Sounds great normally but sometimes the bass gets overwhelmingly loud, and adjusting the gain has no effect on this. It's as if the gain is maxed out and turning the knob has no effect on the volume. One second it will sound fine and the next second it goes crazy.
Note that I installed an on/off switch in the dash to turn on/off power to the tube, since there was no remote accessory wire to tap in to (this is all a bit fuzzy, initial install was a few years ago), so I can just turn off power to the tube when this happens.
Any ideas on what the problem could be? Sometimes the problem goes away overnight, other times I've had luck turning off the power at the tube and leaving it off for a day or so. Could this caused by a loose ground or possibly the switch we installed? Sometimes my driving style seems to bring it on, like when I'm driving on winding roads and take corners a little fast.