Coaxial cable and lower frequencies
Coax does two things.   


Provides a constant impedance so the cable acts as a transmission line
Prevents outside EM interference from coupling into the signal line


First point is a high-frequency phenomenon.  You achieve no benefit in your application

Second point you WOULD get benefit from.  However, you can get the same benefit from a cheaper (and much more flexible) audio-grade shielded wire.  Source a (good quality) guitar or microphone cable and you'll be in business.