Not sure if I'm in the right place but I hope I get the help I need....So I had my subs and amp installed so apon completion the tech turned on the radio and everything working fine. On the way home I switch my source over from fm to bluetooth, major change in sound.. got home and notice that when I use fm radio my subs work perfect but when I use bluetooth from phone subs dont work.BTW while in BT the amp and sub are on but doesn't knock like in fm....i have a 2018 nissan Altima stock stereo 2 12" rockwood fosgate p1, 500w kicker mono amp. I use a galaxy a21 to play bluetooth and i use spotify..think i gave all specs apologies if thread is long