3. I plugged both QC’s into the same wall outlet (not the one with the power strip). I brought up a blank preset with the top path going input 1 to output 1 (mono). I ran an XLR to TS cable from output 1 of the QC to the front of the amp. The hiss increased significantly. I did the same with the QCM and while there is a change is much, much less. This is a HUGE difference. The hiss with the QCM increased a little and it introduced what I think is a little ground hum. This is not an insignificant amount of noise but I suspect it would be similar with about any outboard gear. I’ll try the VP4 in a bit. Again I’m using stock power supplies here which are two-prong.