Cables ehh that old nut again

my background is that I worked in the generation and transmission of Electricity for 25 years, my father was a VERY highly regarded senior Electrical engineer for the C.E.G.B for nearly 50 years.
I believe I approach things with an open mind and cables have always been one area which I have been heavily involved with over many years both at work and at home.
My first question for those who think all cables are the same is why do large cable companies spend millions every year on research into cable technology?
secondly, Why do cable companies spend huge sums of money producing so many different cables? lets face it if they all did the same thing then why manufacture so many different cables ?
why do they go to a great deal of trouble trying to deal with rfi/emi problems ? and why do they use and manufacture special cables for use in Hospitals and other areas sensitive to electrical "contamination" ?
OK so the answer is because cable companies know that certain problems affect certain situations and as such a cable needs to be up to the job. no consider this if this is the case then even to the average layman the reason for this means that not all cable is created equal yes ? and if that is the case certain HiFi companies have also spent plenty on trying different cables,wasn't Mark Levinson insistant that a certain Belden cable was better for his equiptment?
Our UK mains supply is at best a compromise and also once it reaches our house it is compromised even futher, what's more when we get to Electronics that are very sensitive, especialy to things like RFI and EMI then we are going to see differences from one house/system to the next.
So do cables make a difference? yes of course they do
Do some cables sound better than others, well suffice to say they sound different and as we all hear things in a slightly different way I can't answer that question.
when it comes to mains "conditioning" there are companies out there who have spent serious wads of dosh comming up with ways of giving us "cleaner" power
I know many theories and laws of physics etc that say certain things "can't" be possible etc but then I always remember one thing, there is always an exception to the rule :rds2:
Cables do make a difference, I can say this because i've heard it many times over the last 30 years of messing with electronics, and if you notice most HiFi manufactures actually say they don't include cables to allow the user to choose their own as it's down to personal taste.
So do I use special Mains cables ? yes I do, mostley made by me and quite simple and using simple principles, i.e. shielded decent quality cable which I might add isn't very expensive, by adding braiding etc you can make it look expensive but mostly I would say my mains cables cost less than £15 each.
my advice therefore is give em a try, if you hear a change and you like it then get them, don't spend £'s on them, I personally don't believe that a £200 mains cable and a £50 mains cable sound different enough to make it worth while