I only have 1 unit in the car. That's the double DIN cd player(check link at the end) that comes with 98-02 accords. The guy at the shop installed 2 adapters to add 4 RCA inputs. The amp in my car is a 4 channel amp. I'm not sure why the radio works normally but not the cd player. Doesn't the sound come from the same unit? I'm not sure where the switch connects to. If anyone knows anything about this feel free to explain it to me.

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