Possibly is the problem, Doesn't the Delco stereo come with a amp built in to it? If so, that definitely could be the issue. I don't know but I remember the stereos back in the late 80's and 90's and they were notorious for that. People had to put capacitors on the ground wire to stop the whining. Looking forward to replacing the stereo, The system is nice but I like the idea of having Bluetooth calling and streaming music. One thing to keep in mind, if you ever buy a new HU, make sure you get one with an external microphone. The ones with built in mic pick up to much road noise