No need to make the signal travel any further than it needs to. Those black ones they sell with the gold plated ends aren't that bad. I know a few audiophiles with very expensive stereos that are happy with Radio Shack RCA's. Those cords that come with equipment are a joke. I don't know why a manufacturer would even want to give you those things.
Cords are a tough call.
I don't wanna get into it much more. All I really wanted to get across is that you will hear an improvement in detail if you upgrade all your cords. Even most high end gear still comes with junk cords. It's up to you to customize your sound. Ask the experts, use the web, just don't keep using the test cords that came with your gear.