In order to use a snake, any connected source
instrument should be able to either use a balanced cable (e.g.
microphones) or be at line level (e.g. keyboards). If you put the
output of a guitar down a long cable run, you will loose signal
strength and high frequencies.
If you are connecting an acoustic guitar
directly which does not have a low impedance/balanced output, then
you will need to deploy a Direct Injection (DI) Box.
Cables, snakes and DI boxes are available in the
Online Shop -