You connect one end of cable to "OPT" on dvd player, and the other end of cable to "OPT 1", on receiver. Because of the shape of the connectors on the ends of the cable, it will only fit in the holes, one way.If it doesn't slide in the hole, the way you're trying, turn it a quarter turn each time, until it fits. You should hear a little snap noise, when it's in all the way.
You
may have to go into the receiver's setup menus, and assign the OPT 1 input, to DVD. You will have to check the owner's manual, to see how to do this. It's not hard to do.......
You'll probably need to use a yellow composite video cable, or an s-video cable, from the "Monitor Out" on receiver, to the tv, for using the OSD (on screen display), so you can see what you're doing, in the menus.
You'll also probably need to go into the dvd player's setup menus, and set the audio output to "Bitstream" or "Raw" (depending on it's wording), and possibly turn "ON" the DTS, if that's a separate setting. In most players, setting to Bitstream will enable Dolby Digital and DTS.
I hope this helped. Good luck with your new receiver.
