With headlights off I get a buzzing sound.
 

Im getting a buzzing sound in my newly installed amp installation. With headlights on the buzzing go's away but when the daytime running lights kick on there is buzzing. I have no other sounds such as engine wine or other electrical interference. My only thought is the dimming feature of the radio is not grounding to good. When I get time i plan to clean the grounds by the radio unit. Some troubleshooting so far is I pulled the RCA's off my LOC and the noise is still there. And the noise doesn't fluctuate with the engine rpm. Any one have any suggestions?

please describe your system in detail - every component mfr/model, how wired, connectors used, etc.

2012 Lx stock radio to LOC(LC6i), shielded RCA's to Soundstream rub4.600 amp. Power wires down left side and speakers down right side. The wires fron the stock radio to Loc are shielded and grounded to common ground under radio. Due to the weather i havent looked into it much futher. I suspect radio dimming feature may be at the same ground as speaker wires or DRL relay not grounded the best. For now i just drive with the lights on.

the LOC should have different signal ground options you can try.