summing

My current setup goal in my 2020 Lexus ES350 -T1500-bdCP pushing two CompQ 12"s -RD400/4 pushing four 3.5"s -P300z2 pushing two 6"x9"s My current setup is just the mono into the subwoofers. I have noticed that my subwoofers fall off significantly after 55-60hz. I have deduced this to the Mark...