theres 2 references like mark said,, reverse ref at the node,, u want the node optimized 1st,, inject X and get Y in the reciever in the hub site, then get your reverse reference at the node,, use that reverse reference for all reverse amp/ le locations,, u want ref 0 on your meter on all actives using the rev reference,, now all actives reverse runs the same level as the node,, forward references also get at node, just remember a "reference" is just a comparison of what you had and what your reading now :)