To maximize the performance of the BOSS GX-100's AIRD (Augmented Impulse Response Dynamics) technology, set the connected amp to produce a flat, clean tone. Refer to the amp's owner's manual for how to adjust the amp settings.
In addition, configure the OUTPUT SELECT setting on the GX-100 to match the type of amp connected. Refer to "Specify the type of amplifier you have connected" in the GX-100 Reference Manual for details.