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

Just for kicks, I looked at the backs of my components to see how far away the mains plugs are from the interconnect terminals.  All three -- my Mytek Brooklyn BB, my Primaluna Integrated and my Sony CD/SACD player -- have the power connection on the far left, with the component connections as far to the right as reasonably possible.  All this leads me to believe that keeping the mains supply as far as possible from the other connections is accepted practice.

I also believe, power switches and it's wiring, should be designed at the rear of a component, for the reduction of ac related noise, even though it might be an inconvenience with it's daily operation.

My Herron VTPH2A power switch is on the back right corner, right next to the iec. It is a bit of a hassle. But for all the right reasons.

Jeff Smith from Silversmith Audio offered this on another discussion group concerning his Fidelium ribbon speaker cables: he said to wrap them around power cord and hook them up to your speakers and see if you can hear ANY noise without running a source signal through it. He says you will not and therefor the proximity of his cables and power cords do not matter.

The back of my system is a mess of cabling, but they've never given me reason to be concerned. 

I also use a variety of different interconnects but it's the IXOS ones I particularly dislike for their (pre-ghost encounter) Scrooge-like nature. Extremely thick and tight.

I'm putting my trust in the ability of the various manufacturers to have provided decent shielding on each one. They certainly look thick enough.

I have noticed that my current TV antenna cable (co-ax) seems to have more shielding than in previous times, an extra layer of tin foil if I remember correctly.

Does it make a difference?  Not as far as I can tell.

The only cable that does worry me is the one bringing in the internet from the telephone socket. It looks extremely thin and I can't see how it could have much shielding. Still it's the one that came with the router.

Nevertheless when I once changed it for something more substantial (highly rated on Amazon) I found that my internet speeds dropped noticeably. I put that down to the upgraded cable having more individual wires inside than might be good for it.

Things didn't change overnight so it was back to the manufacturer supplied thin grey cable and the usual speeds (16-17Mbps) returned.

For some reason, I guess just for peace of mind, or just in case, I do keep it as far as I possibly can from the a/c power cable (another very thin one). 

Jeff Smith from Silversmith Audio offered this on another discussion group concerning his Fidelium ribbon speaker cables: he said to wrap them around power cord and hook them up to your speakers and see if you can hear ANY noise without running a source signal through it. He says you will not and therefor the proximity of his cables and power cords do not matter.

Brilliant. A dazzling display of logic! What I love about this is we can now also forget about not only noise but distortion. Because hook a cable up and run no signal through it, there’s no intermodulation distortion! No signal, no noise! Wala! Also no total harmonic distortion! This guys a freaking genius! All we have to do to remove noise from our systems is not run music through them~!

Sorry, but anyone thinks this Jeff Smith idea deserves anything more than ridicule, step right up. Defend away. Its garbage. (Also known as marketing, shilling, etc. Because he's talking about "his" cables. As if his and only his are able to defy the laws of physics. Dream on.)