We made test once with a friend, where we could hear a difference.

The setup was a Denon reciever, and one speaker was connected with a random cable, the other one is a pure copper, braided audiophile cable. The pc was connected with toslink to the reciever. Played the music as mono, and we switched between the left-right speakers.

The only difference we could hear were very high pitched glockenspiel sounds from a flac file. That’s all. Any other music sounded the same. But the point was, there is a very little difference, even it’s rare to find a song where you can actually hear it.

This was the thing where it was clearly audible, but I guess you can’t hear it on youtube, as mp3 already cuts off that high pitches: www.youtube.com/watch?v=5Kh-3xkye6A