Hi,
"The biggest issue for me though is how to determine what is actually better rather than just different."
This is almost the crux of the matter. What is more accurate is perhaps the question. I have not tested mains or digital leads but clearly heard a difference with analogue interconnects. I came to the conclusion that what was important was what I could not live with. It does seem at times, though, a futile quest when a recording engineer may choose microphones, interconnects to suit the recording venue and genre; and that is before it hits the mixing desk!
Regards