The GX-10 has an "AC RESONANCE" feature, which lets you alter the sound produced by the pickup on an acoustic-electric guitar, creating a richer sound similar to that obtained with a microphone placed close to the guitar. For the parameters that can be set for AC RESONANCE, see “AC RESONANCE” in the GX-10 Parameter Guide.
Set the input level according to the output level of the acoustic-electric guitar you are connecting. Refer to “Configuring the input to match the instrument you connect” in the GX-10 Reference Manual for how to set the input level.