If your sub. has stereo line inputs and a built-in crossover with line-level high-pass outputs, the hook-up is quite simple. Connect your preamp outputs to the sub,s line inputs , then connect the sub,s line outputs to your pre-amp,s amplifier inputs. Regarding cables,i would use any high quality interconect(how far is your sub?)
ADDING SUBWOOFER
Hi, I need some advice on the best way to hook up a subwoofer to my system. My system consist of Von Schweikert VR6s driven by KR Enterp-rises VT6000 amps and CJ 16LS preamp. What is the best way to hook up a Velodyne HGS 15 sub? Since i have two main out puts, should I use one set of outputs for the sub and the other to the amps or should I use one set of outputs to the sub and use the subs outout to the amps? The other alternative is to use the speaker level input of the sub, but since I have mono blocs I'm not sure how to hook that up either. And what would be the best cables to use for each set up? I just bought the subwoofer, but no cables because I'm not sure of the best way to hook it up. Eventually I will end up with a decent multichannel HT system down the road in increments, but for now Music is my thing.