Hooked up a 12 Rockford p300 powered sub to front speakers via high level inputs. Sub sounds distorted at low volume even with gain/bass boost almost all the way down. Factory head unit has very basic EQ (low/mid/high). Any suggestions
Try to connect an 3.5mm to RCA cable from your phone to the unit to find if the signal is the issue. If polarities are ok, scrutinize the subwoofer. Sometimes the dustcap comes partially undone causing rattle at all volumes. If you dismount it, you could also inspect tinsel leads.