@groundFungus damn...I'm so tired of wires. I read that shielded wires are better between the motor and driver to avoid any signal distortion, so I ordered some of those. I also read that the shielding should be grounded at the driver/power supply end only. Does that mean just running that ground straight to the power supply, or should I connect it to the same driver terminal as the motor ground?
@Railroader I am feeling very frustrated with the whole thing, you're right. Maybe you can help me with the most suspicious part here though: when operating a single motor (motor one, constant clockwise rotation), I get a stall at higher RPMs (I reduced it to an 800 RPM limit in the software now and that seems to avoid it). When I run motor one with motor two (rapid CW-CCW motion) simultaneously, for some reason only motor one stalls but not motor two.