If aftermarket premium power cords work, why won’t short runs of premium XLR cables work?


I have followed many threads, where people swear premium power cables greatly benefit your sound.  I haven’t decided, as the last time I tried a power cable was twenty years ago.  I used a Transparent power cord and was on the fence.  If adding a power cable improves the sound and it’s only the last few feet of your voltage source, what would make extending a premium XLR cable any different?  If I understand the argument, per se, the premium power cord acts as a filter.   XLR cables are mostly unsupcetable to outside interference.   I’m sure I will be versed here one way or the other.
handymann
Whatever boxes are on the cable is not really relevant (and FWIW, they don't really serve a purpose either).

If the equipment supports the balanced standard, then you can use extensions all you like. If the equipment does not, the results are less predictable, but in your case no difference is heard so the answer is 'you're good to go' :)
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In my experience, different XLR do sound very different. I had Kimber Hero, Cardas Parsec, and finally Kimber KS1116. Each a big jump in price, and a good step up in sound.  
If this was the case, then the associated gear didn't support the balanced standard.
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