What's better, one conductor or two conductors for an RCA interconnect?

@atmasphere AFAIK we should write symbols of units named after person with capital unit letter V, kV, A, kA, kHz, kW etc. but spelled out units with lowercase : volts, amperes, ohms, watts. Multiplier doesn’t change that, so it will be kilovolts, kiloohms, kilowatts, kilohertz. The only exception is when unit contains two words like degree Celsius.

Big Volta’s “V” is for DC Volts.

little Volta’s “v” is for AC volts.

Back to the OP’s question…
When a 2 wire and shield cable is used with an RCA it can have the second wire soldered on the “negative”, the positive, or left completely off.

(On an XLR we would solder it to the -180 side.)

It is kind of like 1/2 a transformer, if we look at it like a twisted pair, so I would suggest that one attaches it somewhere. I use the negative side, but the center pin seems like a valid choice.

@jumia

Simple answer to your question is it depends.

There are two standards for RCA. Single ended RCA which uses one wire for signal (the inside pin) and usually is shielded (the outside ring) but the shield is not required for functionality.

The second standard is Differential input RCA which is balanced like XLR and uses two wires to send signal on wire one and inverted signal on wire two. No shield is used.

Both cables will work on any equipment but generally, you will get better results using the correct cable with each standard.

The second standard is Differential input RCA which is balanced like XLR and uses two wires to send signal on wire one and inverted signal on wire two. No shield is used.

There is no standard for balanced differential amplification using an RCA connection. If such a thing is used expect a bit of the Wild West.

Recent answers Have been amazing.

The RCA connector - isn't it designed to accommodate one conductor and then gripping the shield where it is soldered at the base of the connector.  So how does the RCA connector accommodate 2 connectors(positive and negative) and a ground wire.

I really like atmaspere’s answer including discussion about the shield carrying the signal. It made a lot of sense to my simple mind.