I owned a pair of Rockford Fosgate Punch 250a2s from the same time frame as the 800a4 until 2006, and I can not for the life of me remember if those had the built-in EQ from the factory. From what you are describing, it sounds like they do which would be a slight bump at 45 Hz and another bump at 12 kHz. That would account for your pounding on the low frequencies and potentially muddy midrange area.