Okay, so Steinberg responded after 6 days to set up a call time. Three days after that, I finally received the call. Yes, 9 total days…
Jeff from Steinberg went over all of my issues and went through a whole diagnosis. At the point where I got rid of the stock Yamaha XLR to TRS and used some unbalanced instrument cables I had laying around, the monitors worked! Jeff and I narrowed it down to either bad cables or (more than likely) bad XLR ports. I believe the ladder because the possibility of receiving 2 bad cables is less likely than possibly a single XLR port having a faulty ground or something–which would lead to the above issues.
Thanks Steinberg!