XLR cables for a reasonable price?

All XLR cables sound the same?  A fantasy that we all wish were true.  I thought that based on a lot of talk on these forums until I started trying out some different XLR's in my system.  Then I bought some of the top of the line Purist Audio Design cables to go between my preamp and amps.  None of that cheap $100/ft stuff.  These cables cost much more than that- $500/ft and you won't pry these cables out of my hands.  The difference in sound is startling.  The soundstage is totally black.  I thought it was quiet before but not like this.  The bass came alive.  Night and day difference in the bass.  And the highs are so creamy good.  When I hear cymbals I just want to hug myself.  I could go on; but I won't.  High priced, yes but high satisfaction.  Everything matters.

I can see (+), (-), and ground output wires on each the Left and Right PCB inside my DAC.  They are labeled as such on the PCB.  So best I can tell is that it has the signal, 180 out of phase signal and ground going to the XLRs on the back.  I also see some small transformers which I’m guessing go to the RCAs.  That seems to be per the standard.  I have not looked that closely at my preamp, but I will sometime.  In any case these XLR cables make a significant difference in sound with the DAC through the preamp or direct.  (My DAC is a preamp as well.)  My amp are a balanced design too.  This also holds true for vinyl.

What you seem to be implying is that the internal wiring in a balanced amplifier, or preamp is not important either.  Then the question would be how good do the resistors, inductors and capacitors need to be?  Or the PCBs?

I agree with you that internal components are critical but I posit that the external components, such as cables are also important.  

I recall a discussion in the 90s about speaker cables.  The question was most speakers used cheap, thin wire internally to the drivers as well as fairly inexpensive components in the crossovers.  So what was the point of buying expensive speaker cables?

That led me to rewire my fairly expensive speakers at the time.  I rewired them with Monster Cable (the good stuff and boy did it solder easily- thick wire made up of hair sized strands) and used some small film caps as bypass caps on the electrolytics.  It improved the sound some- but not as much as good speaker cables, as I recall.  I don't understand how or why that is.

One question- and it is a valid one is what balanced cables do professional recording use on their microphones?  Is it basic XLR cabling?  That's what many on this forum say.  Studios do not spring for high dollar cabling.  On the other hand, what do some audiophile studios such as David Wilson, Reference Recordings or Chesky Records, etc use?  I have some of those records and they sound really good.

The standard addresses EMI rejection. More to sound quality than noise and interference.  

For example, if one were to compare silver wire XLRs to copper wire XLRs do you really believe there would be no difference in the sound?