The tests noted by Russell appear to be listening tests. I want to see graphed frequency-response tests using the same equipment they use for testing speakers. Measurements can be taken of several different speaker models using several different type of cabling in anechoic chambers.
Everybody might also want to check out
http://sound.westhost.com/cables.htm
Here is a hilarious quote from a section on the link:
"What we do is kind of dirty and stinky," he said. "We say we are starting with a 12 AWG zip cord, and we position a technician behind each speaker to change the cables out." The technicians hold up fancy-looking cables before they disappear behind the speakers. The critics debate the sound characteristics of each wire. "They describe huge changes and they say, 'Oh my God, John, tell me you can hear that difference,'" Mr. Dunlavy said. The trick is the technicians never actually change the cables, he said, adding, "It's the placebo effect."
This one is the most thorough examination of cable theory I've seen yet.
