The last three feet are the most important because that is last section of cable that influences the signal right before it enters the power supplies in your components. Think of all the crap that can contaminate your water. A good filter at the tap will remove 99.999% of the impurities right before it touches your lips. Do you trust the water that flows through 60 miles of pipe that is 50 to 100 years old? I personally do not.
A properly designed cable "can" I did not say "will" (depending on the quality of your equipment and your ability to perceive changes), improve and enhance certain frequencies, lower the noise floor, increase resolution, etc, etc. I am not trying to convince you one way or the other.. Your own ears and experience is more valid than anyone on a forum.
It is possible that the reverse could also happen== bad sound. So much of what we do and experiment with in audio is system dependent and user dependent. We call that SYNERGY. That is one reason why we have forums here and elsewhere and 15,000 manufacturers. There is room at the bar for everyone! All opinions are valid to the owner of said opinion. Just because someone cannot detect a difference does not prove that it does not exist or is not valid to those who do. There are too many things in this world that cannot be proven or seen but we understand them to exist(ie God particle, string theory, anti-matter, miracles, faith).
The best part of all of this is>>>... Try as many of the cables and products as you can from vendors that will allow a 30 or 60 day trial. If you do not hear any differences or perceive any gains you can send them back. Put your stock cables back in and laugh all the way to the bank. Think of how much money you saved and how much time you can now devote to listening to your music and not worrying about making it sound better.
Not having "Golden Ears" can be a blessing, Can it not?