I would say this statement needs to be better defined since we are talking about science and measurements here.
1. You mention they are copper. How about plated copper or copper alloys? Since 100% pure copper does not exist, at what purity do you consider it copper?
2. Proper gauge. What is proper gauge? Could you also show me a test where cable out this "proper gauge" produces an audible difference?
3. I assume stranded means anything that is not solid core. Any measurements to show that there is a difference between solid core and stranded? Do number of strands make any difference?