Good post from @benanders but I really appreciate that the OP recorded voice tracks using different cables so that they could go back and compare the tracks repeatedly. If you are comparing different recorded tracks back to back it removes a lot of the opportunity for bias. My issue with cable enthusiasts is where they disconnect one set of cables, plug in a new much more expensive pair, listen for weeks and claim that once the new cables "broke in" they sounded much better than the original cables.
I had a home recording studio in the 90's and I used this recording technique to compare preamps and microphones (I used a close-miced acoustic guitar which is very revealing). I even used this process to compare the sound of different tubes in a couple of my mic preamps as well as an opamp upgrade on one of my solid state preams. I posted many of these files on a recording forum and invited folks to listen and submit their reactions. Most listeners were surprised that the differences were so obvious. I used Mogami cables exclusively and it never occurred to me to compare XLR cables this way.
FWIW, I've never been able to hear the difference in interconnects. I realize it woulc be a hassle but it would be interesting if @crozbo could post these files so us skeptics could hear for ourselves.
The OP touched on something I have wondered about for years. If cables really make a difference then we should be able to hear the difference between two kinds of cable on the same recorded track. My skeptical nature tells me that if there really were differences in cables audiophiles would have done this and posted the files to prove their point. Sure, cables are "system dependent" but, I'm sorry, that sounds like a cop out to me.
Does anyone know of a well controlled A/B/X test where cable differences were demonstrated? I've never heard of one. I know of dozens of tests where listeners failed to hear a difference but no test in which they were successful.
Lastly, my position is that if audiophiles hear a difference in cables then, for them, the difference exists. Cables seem to give a many of our creed a lot of pleasure and if that's where they want to spend their money then more power to them. I don't know if I'm lucky or cursed that I can't seem to hear the difference.