I see now. Totally with you. TBH I didn't know how "isolated" the various outputs were from one another. What was throwing me off was that this exact same PSU is used in the Aurora mic preamp, but wired more as I had expected (with a separate 24VDC rail for each of the 2 preamps, plus a third, 48VDC rail for phantom), rather than the stacked config in the GTQC.