I just installed an amp to power my door and rear deck speakers and a new more powerful am for my subs (Subs were very underpowered before, using stock head unit with speaker level inputs on both subs) and there is a very loud hissing noise from the speakers and does not seem to be audible from the subs with the amp's crossover set around 150 Hz. It's so loud I can hear it at all volume levels. I discovered last night the sound completely goes away when the headlights get turned on. Both amps are wired to the exact same ground point, so I do not believe I have a ground loop. Anyone know how I might fix this? This is on a 2011 Civic btw.
