Using multi-conductor wire but with only one conductor needed

[disorder]

I have a good amount of this wire: https://www.redco.com/Redco-TGS-01-Single-Channel-Low-Profile-Balanced-Cable.html

If I wanted to use this for a high gain pedal say, because it's shielded, would it be best to use one conductor and ground the other (at one or both ends?)?

Or should I just parallel both conductors and use both for the signal? Is there any possible issue with this?

I'm asking mostly in terms of noise. Thank you.

[Rob Strand]

Generally you don't want to join the cores because it increases the cable capacitance.

Option 1:  connect the unused core to ground but only at one end (usually the end going to the inputs).

Option 2:  leave the unused core hanging.

Either are OK for a single signal cable.   Option 2 has the least capacitance and the cable is symmetrical in behaviour.   Option 1 is preferred when you have more than one signal going down multicore wire as it reduces crosstalk but that doesn't happen in the single signal case.  If the cable is microphonic you might try Option 1 over Option 2.

[MikeA]

You didn't mention or ask about the shield, but for either one of Rob's options, ground the shield at one end for the best noise suppression.

[disorder]

You didn't mention or ask about the shield, but for either one of Rob's options, ground the shield at one end for the best noise suppression.

I guess I should have because Rob's first option leaves me with the questions... if I'm grounding shield at one end, does the unused core get grounded with it at the same end?

[blackieNYC]

Doesn't matter.  There are EMT reverb plates that ground the 1st shield at one end and another ground connector at the other.   Doesn't matter for stomp boxes. 

[anotherjim]

The wire linked has a lapped screen with an additional bare drain wire. So I'd use one signal wire, crop the screen right back and use the drain wire at one end to ground the screen.

[MikeA]

You didn't mention or ask about the shield, but for either one of Rob's options, ground the shield at one end for the best noise suppression.

I guess I should have because Rob's first option leaves me with the questions... if I'm grounding shield at one end, does the unused core get grounded with it at the same end?

<edit> I concur with the above 2 responses on 1st option. I was about to answer on 2nd option and realized I misread your question. 

[Rob Strand]

I guess I should have because Rob's first option leaves me with the questions... if I'm grounding shield at one end, does the unused core get grounded with it at the same end?

For a single-ended audio cable we make connections like a normal guitar cable:
- The shield always gets grounded at both ends.
- The signal core connects to both ends.

The options only apply to the unused core.

There is a third case where you have:
- The signal core connects to both ends.
- The "unused" core gets wired to ground at both ends
- The shield connects to ground at one end.

IMHO, this option isn't the best choice for single ended audio.  For magnetic fields, relying on the twists is probably worst off than relying on the coax as the return.   The impedance of the inner core is going to be higher than the outside braid so any ground currents will cause a bigger signal in the core than the braid.

For balanced lines or even systems which have differential inputs (guitar amps aren't) you can come up with different arguments.