Marketing ploy. I simply use whatever sounds best in a given application. It's rarely from the same manufacturer. If you don't have the time and resources to evaluate many cables and cords, I suppose the next best thing would be to use wire from the same manufacturer. It's a daunting job fine tuning a system with cables and it all has to be done at home in your own system. Using wire from one manufacturer can lead to a specific house sound you may or may not like.
Interconnects and power cables same manufacterer
I was just at a audiophile meeting and one of the speakers was from a well known cable company. He said if you do power cords, interconnects or wall sockets they should all be from the same company. Is what he saying true or is this just a marketing ploy?