Crabby

I have an older Denon DRA-625Ra and I think it's great. On the back it has Pre-out and Main In jacks. Previously they had the little metal jumpers on them. I'm trying to add a sub, a new Klipsch R-120SW. The Klipsch has Left and Right input. According to the Klipsch manual, I go Pre-out on amp to the Left/Right In on the sub. So I do that, and now only sound is coming through the Sub. no sound to my speakers. which work perfectly. I turned the Gain and the Low Pass knobs, no luck. Also, when I unplug the jacks from the Denon, no sound still coming out of amp. But I forgot which way the little metal jumpers go in. Anyone know that? Anyone know what's up with this? Not sure what I'm supposed to do now. Thanks for the help!