80s info RCA cables
 

RCA cables as stereo interconnects are always a compromise especially in an automotive environment. The biggest problem is that there is no third connection to isolate the shield from the signal ground. Manufacturers have different tricks to get around noise problems like floating the signal ground and trying to filter/drain noise from the shield. Mixing equipment from different manufacturers and connecting them with random RCA cables that can have different designs (draining the shield differently) and properties can add to the problems. The best way to avoid some of the problems is to use equipment that has DIN (Euro (German specifically)standard) connections and semi balanced or even fully balanced connections like Zapco used back in then day. To get the best out of interconnects you need to do a bit of research and I would recommend looking into how twisted pair and shielding works, Google CMR-(common mode rejection) there is lots of info on the net but not so much specifically for automotive so better to look at audiophile and pro/commercial audio info. You will probably end up making your own cables.

I've used quality microphone cable with a twisted pair for signal and ground. And a shield layer which is only connected to ground on the source connector.

It's important to distinguish the different applications for twisted pair vs shielded cables.
One is for differential and the other for single ended.
https://youtu.be/QOagVDZLQnA

@Bmwe5320023.0
I specifically started a new thread to avoid the expert (You) who has no idea of what he is doing chiming in with more bullshit.