I have been a stickler about keeping power cables away from signal cables...on equipment ?

I have found that at the end of the day their is somhow a lot of cables in a snake nest behind the system. 
Therefore when it is hard to keep them all a part. I of just that reason keep all of my cables shielded. Both power and signal cables (and speaker cables also).
I think like this that a shielded power cable is not only hindering some noise going into the cable but more important it is also hindering the power cable to make electromagnetic field and disturbing the signal cables in the snake nest when the shield is making it to not radiate that much.
And of course the signal cables is also shielded so all the cables possibility to interfering into each one of the other ones is minimized. 
So that is another reason to use shielded power cables, not that it by it self is doing some magic maybe, it also have some benefit to the whole system indirectly it is another angle that is not discussed so much when often it is the cable it self that is studied and zoomed into, that it will not GET interference. But not what the cable GIVES for electromagnetic field to the environment. And guess what is near in their natural habitat in practice. Yes as we know the snake nest.
But if this has any practical benefit more than a  piece of mind I do not relly known. :D

I too try to keep all of my cabling as separate as possible, but to some extent one can only do so much. I think of it as a best practice type of thing. Might not really help, but certainly can’t hurt.

Correction Millercarbon, 'these things all make difference YOU think you can hear in a non-blind comparison.'

As we age...Rock on..

I toss em this way and that, until I get some hum, then it's a chase, sometimes a long one.

but only had hum from power twice in all the years, and way back when, fm antenna hum (college days, t shaped twin leads taped to something this way or that. coax to real fm antenna solves that.