ground connection on dedicated line?

Thanks guys. Very insightful. It also seems I touched a hot spot for some, and that's fine. It's all well-intended feedback.

I should mention I'm not in the US. So maybe not illegal here. Point taken, though: one ground. What should the resistance be to be considered a good ground?

Alrau1: because I'm not in the US, can you please shed some light on what BX armored cable is, and what Romex is? I'm aware of copper and aluminum shielding, but not sure what BX stands for.

Thanks again

Thanks again guys. You've been very helpful.

Jea48: thanks for spending the time to explain it like that. My second post was submitted before your response was posted. Plus the tip and link regarding polarity are great. I hadn't thought or heard about that.

Regarding BX, I spoke to a couple of local wire manufacturers and they recommend copper armor. Any reactions? I read threads were people mentioned the benefits of running a dedicated line for analog devices and another dedicated line for cd players and other digital devices. They also recommend keeping both lines 18 inches apart to avoid noise induction from one to the other. I need to make both runs inside the same pipe (concrete building). Would the armor prevent noise from the digital-dedicated line to be induced onto the other, and do you believe that noise would be material to sound reproduction?

I apologize to keep asking more questions, but I'm tempted by the great replies.

Regards,
Horacio