If the sub has pre ins and outs you can go from the Adcom to the sub from the pre-outs of the Adcom then from the sub to your main amp. This means that you will be using the crossover in the sub and it may or may not be bad for the sound of your main speakers. I prefer to use "Y" cables if the preamp doesn't have two sets of pre-outs and send one signal to the sub and the other to my main amp. This way the sub can be set to roll off the bass at a low frequency such as 63hz and the main speakers can still run full range without the detrimental effects of the subs crossover.
Some prefer to use the sub crossover to take the bass out of the main speakers because it frees up the midrange and takes some of the strain off of your main amp. You can try it both ways and see which one you like.
Some prefer to use the sub crossover to take the bass out of the main speakers because it frees up the midrange and takes some of the strain off of your main amp. You can try it both ways and see which one you like.