Do you possibly have them running next to your power wire? The stinger cables usually have good insulation, but that's a common problem to run into.
I have the same issue, I know where they cross, just haven't took it apart t fix the problem, but I had to listen to notice it.
Also make sure they aren't touching metal behind your radio, electrical tape the connections just to be safe.
I'd also second Logan's opinion, common Pioneer problem (didn't notice the sig to see h/u, good call)