DVI carries no audio, while HDMI carries both audio and video. I'm thinking that a connection labeled HDMI/DVI is probably intended to carry a video-only signal from a PC so you can use the Samsung screen as a large video monitor for a PC or laptop. Maybe that's why the HDMI/DVI input doesn't carry an audio signal??
AT&T U-Verse Northeast Ohio
Denon x4000, Carver m1.0t, Samsung LED TV, B&W 704 mains, two M&K subwoofers, Oppo 103, Roku 2, etc.
Headphone system: Sennheiser HD600, AKG K702, Hifiman HE-400i, Marantz HD-DAC1 (also used for music playback in the main system, Marantz CD5004, Denon DVD-3910