I have noticed that the red RCA connectors on the 990 are a little more snug then the white. I thought it was the cable at first but all cables I’ve tried do the same thing. I’ve seen cables with the arrows on them but directional cables don’t make sense to me. The audio signal is moving in both directions. At any time the electrons are moving in one direction or the other to create the analog signal. They don’t just move in one direction like DC current would.