Cable management has been a source of hum for me probably twice now, and that sort of interference is the sort of thing that balanced connections were developed to combat so it makes sense that the balanced cables helped.

Auto setup can be quirky with the bass management settings. My rule of thumb when using it is that channel trim and distance settings are pretty reliable (although I still sometimes dust off the SPL meter just to "tweak" a bit) but that bass management decisions are something that I am going to set on my own.