ground connection on dedicated line?

Just connect the dedicated circuit ground back to the main panel.

A quick call to your local municipality will tell you whether you can do otherwise legally. Keep in mind that local electrical codes may add to national codes.

Romex is a brand name but it's often used as a generic name for your basic, standard house wire. BX cable is simply wire in a flexible metal sheathing. It's typically used in garages or inside a house when the wire is not buried in the wall, but is surface mounted. This is often done in older heritage homes that are retrofitted with electricity. Rather than rip up wall or ceiling plaster, surface mounted electrical cables and metal receptacle boxes are used. BX is a flexible metal conduit. Alternatively, rigid metal conduit is used.

Out here in the sticks we like to use BX in the walls, in case we get squirrels.

Lewinski,

Markphd is correct but his response might need clarification. Romex is one brand a type of insulated cable assembly generally containing, within its outer insulating sheath, 2 or 3 insulated conductors and an uninsulated ground conductor.
BX is a brand of steel or aluminum armored flexible conduit with insulated wires inside. In addition to protecting the conductors contained within, the armor serves as a ground conductor.
In the US, Romex and BX are used as generic terms, just like most of us call cellophane tape "Scotch tape" no matter what brand it is.

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

Lewinski,

I, too, vote "yes" on separate lines for analog and digital.

I recommend steel BX (rather than aluminum or copper) because only a ferrous material will block magnetic fields. You should not need the 18" spacing with steel BX (and as Tobias said, it's great for keeping the squirrels from snacking on your wires--copper is soft as well as pricey).