I've been searching online for the answer but no luck so here it goes. My Sony head unit has a rca output for amps to connect. I've ran a mono amp this way for years just fine. However, I decided to run a 4 channel amp on this rca for my door speakers pioneer 6x8 speakers. When I connected the 4 channel amp directly to this rca all I got was bass. I'm thinking the rca output from the head unit is for bass/sub's only so I've considered splicing a pair of rca into the factory speaker wire (disconnected from the speaker but connected to the head unit still). Im thinking the signal used for the factory speakers awas for the highs and the output was for bass only. Would this work to splice?