rbs88

i reset my batt for the 1st time since i bought my 2000 ls400. and after reconnecting the battery i could instantly notice that the rear speakers and sub are noticeably weaker and do not sound the same at all..(everything is factory, speaker/amp/headunit) ive been researching past few hours and could only info i could find was to check the fuses. and on the 2000 im not sure how many there are but i can only find 2 radio fuses.. one under the hood and one under the steering wheel. both are fine. other than that im not sure what to do or what to check. am i missing something? is there an amp fuse??? are there more hidden fuses i didnt look? no factory cell phone either

the fronts sound abnormally loud. the rear is really weak, when i switch the fader f/r,, going to the front its almost no change in sound. and then when putting the fader to the rear, about 80% sound goes away and the sub is working but not thumping how it was literally right before i disconnected the battery..

any tips?