I've done the dic mod and hooked everything up as per instructions. My main problems are even after grounding everything and using an rca noise filter I still have feed back. The worst problem is the quality of the sound. It's almost like an echo or something. The music volume is way louder than the words. I've left everything zeroed out on the factory radio, changed everything possible on the aftermarket. Still no change. Sounds horrible. It's an older unit but works fine. Kenwood ddx419. Any tips would be appreciated. I've done many installs and never had any issues like this. Every connection is soldered and wrapped in heat shrink. I just don't get how it sounds worse than factory. Please help lol

 

Stuff you probably already checked... Does source matter? Speakers anyone(s) worse than others. Speaker wire routing too close to a high current wire? I'm guessing you're an amp. Is the stable voltage when checking power and ground at connector?

 

I've got it wired exactly as I found on another post on here. Using the front pre outs into the factory connection. Still no change.

 

Have you tried a voltmeter connected at speaker terminals and compared voltage at the different speakers?