We received a Samsung Smart TV for Christmas, which was wonderful, but now neither our DVD player nor our Sony surround sound can work because there is no RCA input option on the Smart TV. Only 2 HDMI and one USB. I purchased a RCA to USB cable but the Smart TV doesn't recognize it. I also purchased a RCA to HDMI cable, but it doesn't recognize it either. The converter boxes I've looked at do not seem like they will work and I don't want to continue to purchase needless items. Please help.